Merge branch 'main' into claude/host-management-ui-plan-7f20ab

Seven files needed a hand. Most were two branches adding something in the same
place, but three were one branch changing what the other had moved or renamed,
and those are the ones worth reading.

The shell keeps both new fields and both constructor lines: the connection
recorder this branch built and the teams view model main did. Where main put a
teams load inside OnScreenChanged, it now sits beside the logs refresh rather
than inside RaiseSurfaceState — this branch extracted that notification block
and it is called from two properties, so a screen-specific side effect in there
would fire on every terminal switch as well.

Main gave four row types a vault id and a vault name, and this branch had moved
one of them — KnownHostRowViewModel — into its own file when the pinned keys
became a screen. Git resolved that as "deleted here, modified there" and took
the delete, which compiles as long as nobody looks: the moved copy still had
the two-argument constructor and the call site had grown to four. Carried over
by hand, along with the ordering the pins list now does on them.

The status line's quiet rule was the subtle one. Main extracted it into
IsWorthReporting; this branch had changed the same condition to read item
counts rather than raw ones, because every user action queues a log entry a
moment later and this machine reads its own entries back on the next pull. Take
main's structure and the merge builds, passes, and silently restores a bug this
branch existed partly to fix — every save's message overwritten a second after
it appears. The method now reads PulledItems and PushedItems, with the reason
in its remarks.

Two conflicts were prose that had gone stale rather than code. The keychain
screen's comment said team vaults are refused by the server's access service,
which was true when it was written and is not now; main's replacement stands,
in this branch's vocabulary. The design-gaps row for groups was claimed by both
— real host groups here, per-vault headings there — and they are different
things, so both rows stay and the difference is stated: a group is a shelf the
user chose, a vault is who can read the item.

One defect the tests found and the compiler could not. Generating a key opens
the same editor as pasting one, but not through NewKey — so it never set the
target vault main added, and a generated key was filed into whatever vault was
edited last, or none. Both key-generation tests failed on it. Fixed where the
editor opens, with the reason recorded there.

One gap is left deliberately and is written down rather than half-built. Hosts,
keys, credentials and pins are read across every vault this session holds a key
for; groups are read from the active vault alone, so a host a teammate filed
shows under UNGROUPED. Nothing is lost or misfiled — it is what the sidebar
already shows for a group that has been deleted — but closing it needs a vault
id on every group row for rename and delete, and a way to tell two vaults'
identically-named groups apart under a layout with one heading per group. Both
are worth doing and neither is a merge's business. It is in the remarks on
ReloadGroupsAsync and in docs/design-import-gaps.md.

dotnet build, dotnet test and dotnet format --verify-no-changes are all clean:
1282 tests, including the end-to-end suite against real containers.

src/DodoSSH.Client.App/Views/VaultScreen.axaml

@@ -22,9 +22,10 @@
     behind them, so listing them would be two headings that could never have anything under them. Recorded
     in docs/design-import-gaps.md.
 
-    The SCOPES rail below the categories is the keychain list, which is real and today has one entry in it.
-    The design shows three, two of them teams; team keychains exist as tables on the server and are refused
-    by its access service, so a rail with three entries would be showing two nothing can open.
+    The SCOPES rail below the categories is the keychain list. Since M3 it genuinely has more than one entry
+    when somebody is in a team — but it is still not a selector, because every table on this screen already
+    spans every keychain this session holds a key for and each row names its own. What it carries instead is
+    the one keychain question with an answer: where a new item is filed.
   -->
 
   <Grid ColumnDefinitions="176,*,244">
@@ -91,18 +92,35 @@
           <TextBlock Classes="label" Text="SCOPES" Margin="14,0,14,8" />
 
           <!--
-            One entry per vault this session opened. Not a selector: every list on this screen reads the
-            active vault, and a rail that let you click a vault you cannot switch to would be a control that
-            does nothing. It is here because knowing which vault you are looking at is worth a line, and
-            because this is where a second one appears when shared vaults arrive.
+            Still not a selector. Every list on this screen now spans every vault this session holds a key
+            for, and each row names its own vault — so there is nothing to switch to. What the picker below
+            chooses is where a *new* item is filed, which is a different question and the only one that has
+            an answer worth asking for.
           -->
           <StackPanel Orientation="Horizontal" Margin="14,2" Spacing="7">
             <Ellipse Width="6" Height="6" Fill="{StaticResource Accent}" VerticalAlignment="Center" />
             <TextBlock Classes="mono" Text="{Binding HostsHeading}" FontSize="10"
                        Foreground="{StaticResource Text}" VerticalAlignment="Center" />
           </StackPanel>
-          <TextBlock Classes="hint" FontSize="9.5" Margin="14,6,14,0"
-                     Text="One keychain, because the server grants access to your own and refuses the rest. Sharing is a later milestone." />
+
+          <!--
+            Hidden at one vault, which is where most people stay. A control offering a single option is a
+            question with no answer.
+          -->
+          <StackPanel Margin="14,10,14,0" Spacing="4" IsVisible="{Binding HasVaultChoice}">
+            <TextBlock Classes="label" Text="NEW ITEMS GO TO" />
+            <ComboBox ItemsSource="{Binding TargetVaults}"
+                      SelectedItem="{Binding SelectedTargetVault}"
+                      HorizontalAlignment="Stretch">
+              <ComboBox.ItemTemplate>
+                <DataTemplate x:DataType="vm:VaultChoiceViewModel">
+                  <TextBlock Text="{Binding Display}" FontSize="11" />
+                </DataTemplate>
+              </ComboBox.ItemTemplate>
+            </ComboBox>
+            <TextBlock Classes="hint" FontSize="9.5" TextWrapping="Wrap"
+                       Text="An item filed into a team's vault is readable by everyone holding that vault's key. It defaults to your own and never moves on its own." />
+          </StackPanel>
 
           <!--
             Items that would not decrypt. Shown here rather than only in the status line because this is the