Let a tap on the phone's host list mean connect

Choosing a machine raised the connect bar over the bottom of the list: a
password box, CONNECT, EDIT, MOVE and DELETE. Five controls in the way of the
one thing a tap on a machine's name obviously means.

So the gestures split. A tap connects. A long press raises the bar, with all
five. The pencil in the phone's header — its only persistent chrome — edits
whichever host is chosen, which is the one of the five common enough to be worth
a control that is always in the same place.

The flag doing it is the desktop's own IsHostPaneOpen rather than a second one.
That head made exactly this move when a selection stopped opening its drawer, and
the question both are asking is "has somebody asked about this host" — answering
it twice is how two heads come to disagree about what a selection means.

One tap cannot finish: a host that authenticates with a typed password has
nowhere on a list to be given one. That tap raises the bar with the box in it and
says so, and a second tap with the box filled in connects. The branch is in the
view model rather than in the head, because "can this machine be reached without
asking for anything" is the same question the bar's own password box answers, and
a copy of it in a view would be a second reading of a binding chain that has one.

Two mechanics worth knowing. Avalonia raises Tapped on release whatever the press
lasted, so a long press would open the bar and then connect — one touch firing
both gestures — which is why HostsScreen tracks the hold and swallows the tap it
precedes. And Holding only fires once IsHoldingEnabled is set, so that and the
handler are attached together rather than one in markup and one in code.

ConnectToRecent now opens the pane rather than selecting the row. On the phone it
has to: a selection alone raises nothing now, so going back to a recent machine
would land on a screen with nothing to press.

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

@@ -72,7 +72,7 @@
         <Border Background="{StaticResource Chrome}" BorderBrush="{StaticResource Border}"
                 BorderThickness="0,0,0,1" Padding="14,0" Height="56"
                 IsVisible="{Binding !IsMoreSurface}">
-          <Grid ColumnDefinitions="Auto,*,Auto,Auto">
+          <Grid ColumnDefinitions="Auto,*,Auto,Auto,Auto">
 
             <!--
               Filled rather than outlined since v2. The mark is the one thing on this header that is not a
@@ -100,7 +100,31 @@
               <TextBlock Classes="label" FontSize="9" Text="{Binding SyncLabel}" />
             </StackPanel>
 
-            <Button Grid.Column="3" Classes="icon" Margin="4,0,0,0" Command="{Binding LockCommand}"
+            <!--
+              ◆ THE PENCIL, and it is here rather than on the row for the reason the whole gesture split
+              happened: choosing a host on this head no longer raises a bar carrying EDIT, because that bar
+              was five controls over the bottom of the list in the way of a tap that means "connect". EDIT is
+              the one of the five common enough to be worth a control that is always in the same place, so it
+              is in the header — the phone's only piece of persistent chrome — and the long press still
+              reaches the other four. See HostsScreen.axaml.
+
+              Two conditions, nested rather than combined, because Avalonia's bindings have no "and" and the
+              two belong to different view models: which screen is showing is the shell's question, and
+              whether there is a host to edit is the vault's. That is the same arrangement the header itself
+              is wrapped in one level up.
+
+              Collapsed rather than disabled when there is nothing chosen. A greyed pencil sitting beside the
+              vault's name on every screen would be a permanent reminder of a control that is only ever about
+              one row.
+            -->
+            <Panel Grid.Column="3" IsVisible="{Binding IsHostsShowing}">
+              <Button Classes="icon" Content="✎" FontSize="15" Margin="4,0,0,0"
+                      IsVisible="{Binding Vault.CanEditSelectedHost}"
+                      Command="{Binding Vault.EditSelectedHostCommand}"
+                      ToolTip.Tip="Edit the selected host" />
+            </Panel>
+
+            <Button Grid.Column="4" Classes="icon" Margin="4,0,0,0" Command="{Binding LockCommand}"
                     ToolTip.Tip="Lock the keychain">
               <TextBlock Text="LOCK" Classes="label" FontSize="8.5"
                          Foreground="{StaticResource TextDim}" />