Give the phone the rest of its screens, and a way in

All seven screens of the design, plus the two it does not draw because it starts at an
enrolled phone: naming a server, and choosing a passphrase.

The five states docs/android-port.md worried about losing at 360dp are all here and none
of them softened. The changed-key refusal is a full-screen panel rather than a bottom
sheet, because a sheet is swipe-to-dismiss by convention and that screen must have no way
forward. The recovery code raises FLAG_SECURE for its own state and lowers it afterwards,
so the sentence about screenshots is true rather than decorative. The delete
confirmations keep their counts and replace the row in place.

Signing in works, and the seam it needed is worth more than the implementation:
IAuthorizationCallback now sits between OidcClient and the loopback listener, so the two
heads differ in where the response arrives and in nothing else. PKCE, the state check,
discovery, the token exchange and the key binding stay one implementation — a second OIDC
client would be a second place for a security bug to live. The phone registers a
private-use scheme with the system rather than binding a loopback port, which on a shared
device any other app can do first.

The accessory key row needed TerminalWorkspace.SendInputAsync: ordinary typing goes from
the renderer straight down the socket, and there was no way in for the keys a software
keyboard does not have. Ctrl latches, because one thumb cannot chord, and the latch is
drawn — a modifier that is on and does not look on is how somebody sends ^L to a database
prompt believing they typed an l.

597 client tests green, including two new ones for the input path and one for the
terminal surface command. Nothing has run on a device.

src/DodoSSH.Client.Session/ServerConnection.cs

@@ -270,7 +270,8 @@ public sealed class ServerConnection : IVaultServer
         Uri serverUrl,
         IBrowserLauncher browser,
         TimeProvider clock,
-        CancellationToken cancellationToken)
+        CancellationToken cancellationToken,
+        Func<OidcClientOptions, OidcClientOptions>? configureOidc = null)
     {
         ArgumentNullException.ThrowIfNull(serverUrl);
         ArgumentNullException.ThrowIfNull(browser);
@@ -287,7 +288,17 @@ public sealed class ServerConnection : IVaultServer
 
             var meta = await discovery.GetMetaAsync(cancellationToken).ConfigureAwait(false);
 
-            var oidc = new OidcClient(transport, browser, clock, BuildOidcOptions(configuration));
+            // The head gets a say in how the authorization response comes back, and in nothing else.
+            // Everything that decides whether the flow is *safe* — PKCE, the state check, the discovery
+            // document, the token exchange — is built from the server's own configuration above and is not
+            // reachable from here. See OidcClientOptions.CallbackFactory.
+            var oidcOptions = BuildOidcOptions(configuration);
+
+            var oidc = new OidcClient(
+                transport,
+                browser,
+                clock,
+                configureOidc is null ? oidcOptions : configureOidc(oidcOptions));
 
             var tokenSet = await oidc.SignInAsync(cancellationToken).ConfigureAwait(false);