Invite links: starsync:// opens the app and asks to join; one app per profile; real invite address; clipboard pick-up

- starsync://host:port/?name=&pw= (PROTOCOL.md "Invite link"); the password only when ticked, never in logs
- Linux: launcher entry takes x-scheme-handler/starsync (%u, StartupNotify) and becomes its xdg-mime default; Windows: HKCU\Software\Classes\starsync -> starsync.exe
- InstanceLock: lock file + loopback handoff per profile folder; the running app comes up with the second start's activation token (Wayland/X11) or AllowSetForegroundWindow (Windows)
- Sharing looks up the internet address (HTTPS services with fallbacks); members card picks Internet / Home network / VPN and says when the port needs forwarding
- JoinOffers: link and clipboard prompt with /health, joins through ConnectFlow; dismissed clipboard invites kept as fingerprints

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/desktop/test/test_graph.dart

@@ -6,9 +6,13 @@ import 'package:starsync/src/session/identity.dart' show ClientIdentity;
 
 /// One graph per test file, like the app's one per run: nothing starts
 /// until a test calls `navigation.start()` (or `goHome`), so widget tests
-/// see the app before your server is up.
-AppGraph testGraph({HealthGetter healthGet = defaultHealthGet}) =>
-    AppGraph.build(identity: ClientIdentity.ephemeral(), healthGet: healthGet);
+/// see the app before your server is up. Sharing looks up no internet
+/// address unless [publicAddress] gives one.
+AppGraph testGraph({HealthGetter healthGet = defaultHealthGet, Future<String?> Function()? publicAddress}) =>
+    AppGraph.build(
+        identity: ClientIdentity.ephemeral(),
+        healthGet: healthGet,
+        publicAddress: publicAddress ?? () async => null);
 
 /// [child] under [graph]'s [AppScope].
 Widget scoped(AppGraph graph, Widget child) => AppScope(graph: graph, child: child);