Say how far a connection has got while it is still being made

The connecting card set its status string once, when the tab was created, and
never touched it again. Every connection therefore looked identical from the
outside: one three seconds into a key exchange, one waiting out a fifteen-second
timeout against a machine that is asleep, and one that had hung all drew the
same "connecting…". The card now draws the five steps of getting there, each lit
at the moment the handshake reports reaching it, over an amber track that fills
as they finish.

◆ NOTHING ON THE LIST IS INVENTED. Every row changes state because a layer below
it said so, at the instant the thing it names actually began.

That is the whole reason it is worth showing, and it is why most of this commit
is plumbing rather than XAML: there was no progress reporting anywhere in the
stack to hook a step list onto, and a card animating plausible progress would
have been indistinguishable from one that had stopped receiving any.

SshConnectionPhase names four phases and deliberately not more. SSH.NET runs the
entire handshake inside one ConnectAsync and raises exactly one event from the
middle of it — HostKeyReceived, once the key exchange has produced a key to show
— so that event is the only interior moment there is to report. Everything
before it is Reaching and everything after it is Authenticating. A fifth phase
in that assembly would have to be a timer, so there is not one. OpeningShell is
reported by TerminalWorkspace instead, because that is where it happens: the
factory's work ends with an authenticated connection, and asking for a
pseudo-terminal on one is a separate round trip. The SFTP path passes null — a
second connection opened behind an already-open shell has nobody watching a step
list for it.

The card's fifth step, "Starting the terminal", is the renderer wait and lives
in the shell rather than in the SSH assembly, which has never heard of a
renderer. On the first connection after a cold start it is a real wait with a
real failure mode of its own — a missing WebView2 runtime — so a list that began
at "reaching the host" would leave the one wait most likely to hang unnamed.

Amber for the step in flight, and that follows the palette's rule rather than
bending it. Green is what is true and purple is what you can press; a step still
happening is neither, and it is exactly the caveat-worth-reading that amber
exists for. Steps behind it go green as they become true. Nothing animates,
which is the argument TransfersScreen.axaml already makes for its own track,
reaching a screen with far more reason to want a spinner: a spinner is furniture
invented to fill a state nobody measured, and these states are measured, so the
track fills to what has finished and then waits there.

A refusal keeps the step it stopped on, in red, with the ones behind it still
green. That is the half a progress bar could not do, and it is the difference
between "that host is not there" and "that host is there and would not have me"
— a question the reason sentence alone frequently does not settle.

The strip's dot goes amber while a tab is connecting, on both heads. It was
grey, and so is a tab whose shell has exited: the two states in that strip with
the least in common, one worth waiting for and one over. PhoneShell's own
comment already recorded half of this — the dot stopped being green before
anything had answered — and this is the other half.

Progress is raised inline rather than through System.Progress<T>, which captures
whatever synchronisation context it was constructed on and posts to it. That
reads like a convenience and is really a second place the marshalling decision
gets made: silently, differently under a test with no context, and out of order
with respect to the failure that follows a phase. The shell marshals once, in
one handler, through a new optional post parameter on MainWindowViewModel — the
same seam TransfersViewModel already uses, and for the reason its own remark
gives. The three Dispatcher.UIThread.Post calls that predate it are the ones
this suite's comments record as out of reach; they are left alone rather than
swept in here.

Both heads draw the list. They differ in one place: Phone.axaml's mono class
sets a colour and a size along with the family, so the caption rule names its
own family instead of composing the two and asking two rules for one Foreground.
The desktop's mono sets the family alone, which is why ConnectingCard does
compose them. Each head also gains SHOW LOGS beside the button that gives up —
the step list is this attempt and the log is every other one, which is what a
connection taking too long actually raises.

Seven tests, and the two that matter most run against the container rather than
a fake: a real handshake reports its phases in order, and a host-key refusal
never claims to have authenticated. A fake asserting what it was written to
assert would have established nothing about either. The rest cover the tab
advancing while the connection is gated, the step a refusal stops on, and a
phase reported after the user has given up on the tab. 1,861 tests, none
failing.

The Android head's layout is not verified by anything. It compiles, and
compiled bindings mean every new binding path resolves, but that project is not
in DodoSSH.slnx, there is no test project for it and no device here — so unlike
the desktop card, whose shapes the layout harness measures, these rows have not
been drawn. Vertical fit is reasoned, not observed.

src/DodoSSH.Client.Shell/ViewModels/VaultViewModel.cs

@@ -943,6 +943,31 @@ internal sealed class ConnectionAttemptEventArgs(Guid attemptId, string label, s
     internal string Address { get; } = address;
 }
 
+/// <summary>A connection that has got as far as a named step.</summary>
+/// <param name="attemptId">The attempt this is about.</param>
+/// <param name="step">The step that has just begun.</param>
+/// <remarks>
+/// <para>
+/// The fourth of the attempt events, and the only one that can be raised more than once for an attempt. It
+/// exists because the other three say a connection started and then, seconds later, whether it worked — and
+/// the seconds in between are the whole of what a user staring at a connecting card is trying to find out.
+/// </para>
+/// <para>
+/// <b>Raised on whichever thread the handshake is on.</b> SSH.NET reports the interior of a connection from
+/// its own thread, and this event is that report forwarded rather than a copy made on a timer, so a
+/// subscriber that touches a view model must marshal for itself. <c>MainWindowViewModel</c> does; see the
+/// handler.
+/// </para>
+/// </remarks>
+internal sealed class ConnectionProgressEventArgs(Guid attemptId, ConnectionStep step) : EventArgs
+{
+    /// <inheritdoc cref="ConnectionAttemptEventArgs.AttemptId" />
+    internal Guid AttemptId { get; } = attemptId;
+
+    /// <inheritdoc cref="ConnectionProgressEventArgs" path="/param[@name='step']" />
+    internal ConnectionStep Step { get; } = step;
+}
+
 /// <summary>A connection that was asked for and did not happen.</summary>
 /// <param name="attemptId">The attempt that has just ended.</param>
 /// <param name="reason">What to say about it, in the tab.</param>
@@ -4127,6 +4152,15 @@ internal sealed partial class VaultViewModel(
     /// </remarks>
     internal event EventHandler<ConnectionAttemptEventArgs>? ConnectionStarting;
 
+    /// <summary>Raised as a connection this vault announced gets from one step to the next.</summary>
+    /// <remarks>
+    /// Between <see cref="ConnectionStarting"/> and whichever of the other two ends the attempt, any number
+    /// of times including none — a handshake fast enough to finish inside one turn reports nothing, which is
+    /// the honest account of it. See <see cref="ConnectionProgressEventArgs"/> for the threading, which is
+    /// the one way this event differs from its three neighbours.
+    /// </remarks>
+    internal event EventHandler<ConnectionProgressEventArgs>? ConnectionProgress;
+
     /// <summary>Raised when a connection this vault announced does not become a session.</summary>
     /// <inheritdoc cref="ConnectionStarting" path="/remarks" />
     internal event EventHandler<ConnectionFailedEventArgs>? ConnectionFailed;
@@ -10889,6 +10923,53 @@ internal sealed partial class VaultViewModel(
         return true;
     }
 
+    /// <summary>Turns the handshake's phases into this attempt's progress events.</summary>
+    /// <remarks>
+    /// <para>
+    /// Forwarded rather than accumulated, because the tab is the thing that knows what has already happened
+    /// and this object deliberately does not: a connection here is one straight line from renderer to
+    /// session, and a running total of where it had got to would be a second copy of the state the card
+    /// already draws from the first.
+    /// </para>
+    /// <para>
+    /// <b>Deliberately not <c>System.Progress&lt;T&gt;</c></b>, which captures whatever synchronisation
+    /// context it happens to be constructed on and posts to it. That reads like a convenience and is really
+    /// a second place the marshalling decision gets made: silently, differently under a test with no
+    /// context, and — because a post is a later turn — out of order with respect to the failure or the
+    /// session that follows the phase. Raised inline instead, and the shell marshals once where it can be
+    /// seen. See <c>MainWindowViewModel.OnVaultConnectionProgress</c>.
+    /// </para>
+    /// </remarks>
+    private PhaseReporter ReporterFor(ConnectionAttemptEventArgs attempt) => new(phase =>
+        ConnectionProgress?.Invoke(this, new ConnectionProgressEventArgs(attempt.AttemptId, StepFor(phase))));
+
+    /// <summary>The step a handshake phase is reported to the shell as.</summary>
+    /// <remarks>
+    /// The whole of the mapping between the SSH assembly's four phases and the card's five steps, in one
+    /// place. <see cref="ConnectionStep.PreparingTerminal"/> is not here because nothing reports it: the tab
+    /// starts on it, and the first phase to arrive is what closes it.
+    /// </remarks>
+    private static ConnectionStep StepFor(SshConnectionPhase phase) => phase switch
+    {
+        SshConnectionPhase.Reaching => ConnectionStep.Reaching,
+        SshConnectionPhase.CheckingHostKey => ConnectionStep.CheckingHostKey,
+        SshConnectionPhase.Authenticating => ConnectionStep.Authenticating,
+        SshConnectionPhase.OpeningShell => ConnectionStep.OpeningShell,
+        _ => ConnectionStep.Reaching,
+    };
+
+    /// <summary>Hands each phase straight to a delegate, on the thread that reported it.</summary>
+    /// <remarks>
+    /// The whole type, and it exists to be the thing <c>System.Progress&lt;T&gt;</c> is not — see the remark
+    /// at its one use. A lambda cannot implement an interface, and the alternative was widening the
+    /// workspace's parameter to <c>Action&lt;T&gt;</c>, which would have put a non-standard progress
+    /// contract into three assemblies to save one class here.
+    /// </remarks>
+    private sealed class PhaseReporter(Action<SshConnectionPhase> report) : IProgress<SshConnectionPhase>
+    {
+        public void Report(SshConnectionPhase value) => report(value);
+    }
+
     /// <summary>What a manual target reads as, once it has been taken apart.</summary>
     /// <remarks>
     /// Separate from <see cref="ConnectionTarget"/> because a keychain host has no username of its own at
@@ -11238,6 +11319,8 @@ internal sealed partial class VaultViewModel(
         HostAuthentication authentication,
         CancellationToken cancellationToken)
     {
+        // Not reported before the await: the tab is constructed with this step already running — see
+        // TerminalTabViewModel — because there is no moment between the two worth telling anybody about.
         await workspace.WaitForRendererAsync(cancellationToken).ConfigureAwait(true);
 
         var request = new SshConnectionRequest(
@@ -11247,7 +11330,7 @@ internal sealed partial class VaultViewModel(
             authentication.Credential);
 
         var sessionId = await workspace
-            .OpenSessionAsync(request, TerminalSize.Default, cancellationToken)
+            .OpenSessionAsync(request, TerminalSize.Default, ReporterFor(attempt), cancellationToken)
             .ConfigureAwait(true);
 
         // The workspace has already opened a ticket for this session, with the address and the moment it