Merge branch 'main' into claude/vault-unlock-logout-autosync-a84c35

Four files needed a hand, and all four were two branches adding something in
the same place rather than either changing what the other did.

The shell's constructor now takes both new parameters: main's SFTP session
factory, which it must have because it builds the transfers view model, and
this branch's optional resume handler, which stays last so every existing test
that constructs a shell without one still gets a shell that can only be online
because somebody signed in during this run. App.axaml.cs, ShellFlowTests and
QuickConnectTests pass the pair; the layout suite keeps both of its new fields.

Signing out now detaches the transfers screen exactly as locking does, and the
confirmation says that an open transfer session survives it. That is the same
policy both sides already argue for their own case: signing out destroys this
machine's copy of the vault, not work that authenticated before it.

QuickConnectTests did not compile on main — the SFTP commit added a constructor
parameter and the quick-connect suite, merged from a parallel branch just
before it, was still calling the old one. Fixed here rather than worked around,
since the merged tree has to build.

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

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

@@ -184,20 +184,15 @@
           </Grid>
 
           <!-- ============ FILES ============ -->
-          <views:NotBuiltScreen IsVisible="{Binding IsTransfersScreen}"
-                                Title="FILE TRANSFER"
-                                Milestone="MILESTONE M2"
-                                Summary="The design shows a two-pane file browser over SFTP with a transfer queue. None of it is here: an SSH connection in this build opens exactly one interactive shell channel and nothing else, so there is no file transfer to show the state of."
-                                Instead="Until this lands, move files the way you would from any terminal — scp or rsync from a shell on this machine, or a shell open on the host itself.">
-            <views:NotBuiltScreen.Missing>
-              <sys:List x:TypeArguments="x:String">
-                <x:String>An SFTP subsystem channel on ISshConnection, which today offers OpenShellAsync and nothing more (DodoSSH.Client.Ssh).</x:String>
-                <x:String>Remote directory listing — names, sizes, modification times and permission bits (DodoSSH.Client.Ssh).</x:String>
-                <x:String>A transfer queue with progress, throughput and resume, and somewhere for it to live across a lock (DodoSSH.Client.Ssh, DodoSSH.Client.Session).</x:String>
-                <x:String>Routing a transfer through a bastion, which needs jump-host support the connection layer does not have — the host model already records the chain.</x:String>
-              </sys:List>
-            </views:NotBuiltScreen.Missing>
-          </views:NotBuiltScreen>
+          <!--
+            Wrapped rather than bound directly, for the same reason the vault screen is: this element's
+            visibility is the shell's business and its data context is the transfers view model, and putting
+            both on one element resolves IsVisible against that view model, where IsTransfersScreen does not
+            exist.
+          -->
+          <Panel IsVisible="{Binding IsTransfersScreen}">
+            <views:TransfersScreen DataContext="{Binding Transfers}" />
+          </Panel>
 
           <!-- ============ VAULT ============ -->
           <!--