feat: support smol:// QR sharing, deep links and in-dialog scanning

test/widget_test.dart

@@ -1,5 +1,6 @@
 import "dart:io";
 
+import "package:app_links_platform_interface/app_links_platform_interface.dart";
 import "package:flutter_riverpod/flutter_riverpod.dart";
 import "package:flutter_test/flutter_test.dart";
 import "package:hive_flutter/hive_flutter.dart";
@@ -10,11 +11,22 @@ import "package:smol_mail/smol/store.dart";
 
 late final SmolStore store;
 
+// AppWidget subscribes to app_links on boot; in the test shell there is no
+// platform plugin to talk to, so the subscription points at this no-op.
+class _NoopAppLinks extends AppLinksPlatform {
+  @override
+  Future<Uri?> getInitialLink() async => null;
+
+  @override
+  Stream<Uri> get uriLinkStream => const Stream.empty();
+}
+
 void main() {
   // Hive's box opening is real file IO, which never completes inside a
   // testWidgets fake-async zone — so it happens here, outside one.
   setUpAll(() async {
     TestWidgetsFlutterBinding.ensureInitialized();
+    AppLinksPlatform.instance = _NoopAppLinks();
     final dir = await Directory.systemTemp.createTemp("smol-widget-test");
     Hive.init(dir.path);
     store = await SmolStore.open(dbPath: "${dir.path}/widget.db");