Make Connections the place a connection is made, and put the keychain away

Four changes to the phone, and the last one needed the connect path taking
apart.

**The bottom bar is three entries.** The keychain moved onto the hub, which is
now SETTINGS with a gear rather than MORE with a hamburger. A bottom bar is for
the places a session moves between, and keys, credentials and tags are managed
occasionally and then left alone — which is the shape of everything already
behind that hub. With the keychain on it, "more" stopped being a description of
what is there. `ShellScreen.Vault` joining `IsMoreSurface` is the whole of the
change: the tab that lights, the header that stands down and the back gesture's
first case all read that one property, which is why the switch mirrors it by
construction rather than by a second list. The keychain screen grew the header
every hub screen has, because the shell's own is not above it any more and
without one there would be no back arrow and nothing saying what the list is.

The desktop keeps its Keychain rail entry. A rail with nine slots has room, so
this is the second thing the two heads arrange deliberately differently, after
the hub itself.

**Terminal became Connections**, and the word does more work than a rename
usually does — see below. The enum member stays `ShellSurface.Terminal`, for
the reason the tab was never called Vault: the surface is a terminal, and the
word a user reads is the product's.

**The + puts the software keyboard away.** It sits above a terminal somebody is
typing into, so the sheet it raises was arriving underneath a keyboard covering
the half of the screen the sheet is on — and worse, laid out into the strip
left above it, since the keyboard's inset shortens everything this head draws.
Avalonia cannot do this and it is worth knowing why: `TopLevel.InputPane`
reports the keyboard and offers nothing that closes one, because the framework's
model is that it belongs to whatever has focus — and this keyboard was raised by
the `WebView`'s own text input, by a native view Avalonia's focus manager never
owned. Clearing Avalonia's focus leaves it exactly where it is. So
`Platform/SoftKeyboard.cs` asks `InputMethodManager`, off the decor view's
window token, and every step of it is allowed to be absent.

**With nothing open, Connections is a connect screen rather than an empty
state.** A box taking `user@host` or `user@host:port`, a password, and the
machines most recently connected to underneath. The box is the only path in this
product to a machine the keychain has never heard of, which is a real case it
had no answer for: an address somebody was handed five minutes ago. A typed
password and nothing else — offering the keychain's keys would be a second
binding resolution beside `TryBuildAuthentication`, and the argument against a
second one is written there at length. Nothing typed is saved, and the screen
says so: a machine worth keeping belongs on HOSTS, where it can carry a key, a
group's defaults and a name.

The recents come out of the vault's own connection log rather than a list kept
in this process, so they survive a restart and arrive on a new phone with the
keychain. Deduplicated by address, because this is a list of places and not of
events, and capped at six so the box stays above the keyboard. Emptied when the
vault is — they are decrypted entries naming where somebody works, and a lock
that left them on screen would be a list still readable after every key that
decrypted it was zeroed. Tapping one leads to whichever of two things it is: a
keychain host goes to that host's connect bar, where its key, its password box
and its refusals already live, and an address goes back into the box, without
the password, whose absence is the point of that path rather than a gap in it.

**The connect path was shaped like `HostRowViewModel` all the way down.** The
log entry, the identification, the failure record and the retry all took a row.
They take a four-field `ConnectionTarget` now, so a connection to an address
shares the ladder of refusals, the host-key question and the tab's lifecycle
rather than growing a second copy of them. `ConnectionRecorder.Record` and
`Identify` have always taken a nullable host id, so the log could already hold a
connection with no item behind it.

One behavioural change falls out of that and it is the one to know about:
**trusting a host key now retries the attempt that raised the question** instead
of re-running whichever host is selected. That was correct while a selected host
was the only way to connect; with a manual target it would dial a different
machine, or refuse with "choose a host first" over a key the user has just
agreed to trust. The test selects a host first, so a regression cannot pass by
connecting to the wrong thing successfully.

`LogsViewModel.ReloadAsync` split so the connections half can be read alone.
Reading the keychain's activity for a screen that offers neither would double
the decryption on the list that was already the expensive one.

Twelve tests: the parse grammar as a theory over seven refusals, the dialled
request, the retry, and both branches of tapping a recent row. The recents rows
are built by hand rather than connected-and-closed — what those tests are about
is which branch a row takes, and driving it through the recorder's queue would
test the recorder, which `DodoSSH.Client.Session.Tests` already does. What needs
a device is phases 11.6 to 11.9 of `docs/manual-checks.md`.

src/DodoSSH.Client.Android/Views/TerminalScreen.axaml

@@ -144,8 +144,12 @@
           are a matched pair at either end of one bar — one leaves this surface, one adds to it — and an
           accented + would rank itself above the way out. The accent fill belongs to the floating + on
           HOSTS, which is the only action on its screen; this one is not.
+
+          Click as well as Command, and the handler does one thing the command cannot: put the software
+          keyboard away. See OnConnectMenuRequested.
         -->
         <Button Grid.Column="2" Classes="icon" Content="+" Height="34" Margin="0,0,4,0"
+                Click="OnConnectMenuRequested"
                 Command="{Binding OpenConnectSheetCommand}" />
       </Grid>
     </Border>
@@ -154,14 +158,107 @@
     <Panel Grid.Row="1">
 
       <!--
-        The empty state, and it says what the surface is for rather than that it is empty. A phone opens
-        here on a cold start, so this is the first thing a new user reads.
+        ============ nothing open ============
+
+        Not an empty state any more, and that is what the bottom bar's word change is about: with no shell
+        running this surface is where a connection is made rather than a page apologising for having
+        nothing on it. Two things are offered, in the order somebody reaches for them.
+
+        A box, because the case this application had no answer for is the address somebody has just been
+        given. Everything else here starts from a keychain item, which is right for a machine used twice and
+        is several screens of work for one used once.
+
+        And the machines already connected to, under it, because that is the commoner half by far: the
+        thing most likely to be wanted is the thing that was wanted yesterday. They come out of the vault's
+        own connection log — see MainWindowViewModel.RecentConnections — so they survive a restart and
+        arrive on a new phone with the keychain, which a list kept in this process would not.
       -->
-      <StackPanel IsVisible="{Binding !HasTabs}" VerticalAlignment="Center" Margin="24" Spacing="10">
-        <TextBlock Classes="title" FontSize="13" Text="NO SHELL OPEN" />
-        <TextBlock Classes="body"
-                   Text="Press + above, or choose a host and press CONNECT. A shell opened here keeps running while the app is in the background, and keeps running after the keychain is locked — a notification says so for as long as one is alive." />
-      </StackPanel>
+      <ScrollViewer IsVisible="{Binding !HasTabs}">
+        <StackPanel Margin="20,18,20,24" Spacing="10">
+
+          <TextBlock Classes="title" FontSize="13" Text="CONNECT TO A MACHINE" />
+
+          <!--
+            The manual target. One box in the grammar people already have — user@host, or user@host:port —
+            rather than three, because three boxes on a phone is three taps between three keyboards for
+            something that arrives as one string.
+          -->
+          <TextBox Classes="field" Text="{Binding Vault.ManualTarget}"
+                   PlaceholderText="user@host or user@host:port">
+            <TextBox.KeyBindings>
+              <KeyBinding Gesture="Enter" Command="{Binding Vault.ConnectManuallyCommand}" />
+            </TextBox.KeyBindings>
+          </TextBox>
+
+          <!--
+            A typed password and nothing else. Offering the keychain's keys here would be a second binding
+            resolution beside the one the connect path already has, and a key is the reason to save the
+            machine as a host rather than dial it from a box.
+
+            Classes="secret" and not merely PasswordChar: the class is what also tells the software keyboard
+            this is not prose, which is the difference between dots on screen and dots on screen with the
+            password in the IME's dictionary. See Theme/Phone.axaml.
+          -->
+          <TextBox Classes="field secret" Text="{Binding Vault.ManualPassword}"
+                   PlaceholderText="password">
+            <TextBox.KeyBindings>
+              <KeyBinding Gesture="Enter" Command="{Binding Vault.ConnectManuallyCommand}" />
+            </TextBox.KeyBindings>
+          </TextBox>
+
+          <Button Classes="primary" Content="CONNECT" Command="{Binding Vault.ConnectManuallyCommand}" />
+
+          <!--
+            Beside the box rather than on the shell's status line. What fails here is about what was typed —
+            a missing account, a port that is not a number — and a sentence about a text box belongs under
+            the text box.
+          -->
+          <TextBlock Classes="detail" TextWrapping="Wrap" Foreground="{StaticResource WarnText}"
+                     Text="{Binding Vault.ManualStatus}"
+                     IsVisible="{Binding Vault.ManualStatus, Converter={x:Static StringConverters.IsNotNullOrEmpty}}" />
+
+          <TextBlock Classes="body"
+                     Text="Nothing typed here is saved. A machine worth keeping belongs on HOSTS, where it can carry a key, a group's defaults and a name." />
+
+          <!-- ============ where you have been ============ -->
+          <StackPanel Spacing="2" Margin="0,14,0,0" IsVisible="{Binding HasRecentConnections}">
+
+            <TextBlock Classes="label" Text="RECENT" Margin="0,0,0,4" />
+
+            <ItemsControl ItemsSource="{Binding RecentConnections}">
+              <ItemsControl.ItemTemplate>
+                <DataTemplate x:DataType="vm:ConnectionLogRowViewModel">
+                  <!--
+                    Tapping one does not connect, and that is deliberate rather than a missing step. A row
+                    that names a keychain host goes to that host with its connect bar — which is where its
+                    key, or its password box, or its refusal lives — and one that names only an address goes
+                    back into the box above, without the password, which was never stored. Either way what
+                    happens next is visible before anything is dialled. See ConnectToRecentCommand.
+                  -->
+                  <Button Classes="row" MinHeight="52" Padding="12,8" CornerRadius="10"
+                          Command="{Binding $parent[views:TerminalScreen].((vm:MainWindowViewModel)DataContext).ConnectToRecentCommand}"
+                          CommandParameter="{Binding}">
+                    <Grid ColumnDefinitions="*,Auto">
+                      <StackPanel Grid.Column="0" Spacing="2" VerticalAlignment="Center">
+                        <TextBlock Classes="mono" FontSize="13" FontWeight="SemiBold"
+                                   Text="{Binding HostLabel}" TextTrimming="CharacterEllipsis" />
+                        <TextBlock Classes="detail" FontSize="10.5" Text="{Binding Address}"
+                                   TextTrimming="CharacterEllipsis" />
+                      </StackPanel>
+                      <TextBlock Grid.Column="1" Classes="detail" FontSize="10"
+                                 VerticalAlignment="Center" Text="{Binding Started}" />
+                    </Grid>
+                  </Button>
+                </DataTemplate>
+              </ItemsControl.ItemTemplate>
+            </ItemsControl>
+          </StackPanel>
+
+          <TextBlock Classes="body" Margin="0,10,0,0"
+                     Text="A shell opened here keeps running while the app is in the background, and keeps running after the keychain is locked — a notification says so for as long as one is alive." />
+
+        </StackPanel>
+      </ScrollViewer>
 
       <!--
         A tab with no pane behind it: one still connecting, or one that was refused. The desktop head draws