feat: add-account wizard, edit account, inbox tap, connection status

- Add account wizard: email-first flow with JMAP/IMAP auto-detection
  via well-known URLs; falls back to manual type selection
- Fix JMAP connection probe: GET session URL with Basic auth instead
  of the API endpoint, so 401 reliably signals bad credentials
- Account list tile: tap → open INBOX directly; popup menu for
  all mailboxes / edit / delete (with confirmation dialog)
- Show account type (JMAP/IMAP) and async connection status per tile:
  spinner while checking, green check on success, red error on failure
- Add EditAccountScreen: edit name, password, server settings; runs
  connection test only when password is changed
- Fix GTK window initialisation order so app starts with correct size
- Fix 42 lint issues (avoid_redundant_argument_values,
  unnecessary_non_null_assertion, unawaited_futures)
- 147 tests, 87% coverage, task check green

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

test/widget/helpers.dart

@@ -9,14 +9,19 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
 import 'package:sharedinbox/core/models/account.dart';
+import 'package:sharedinbox/core/models/discovery_result.dart';
 import 'package:sharedinbox/core/models/email.dart';
 import 'package:sharedinbox/core/models/mailbox.dart';
 import 'package:sharedinbox/core/repositories/account_repository.dart';
 import 'package:sharedinbox/core/repositories/email_repository.dart';
 import 'package:sharedinbox/core/repositories/mailbox_repository.dart';
+import 'package:sharedinbox/core/services/account_discovery_service.dart';
+import 'package:sharedinbox/core/services/connection_test_service.dart';
+import 'package:sharedinbox/di.dart';
 import 'package:sharedinbox/ui/screens/account_list_screen.dart';
 import 'package:sharedinbox/ui/screens/add_account_screen.dart';
 import 'package:sharedinbox/ui/screens/compose_screen.dart';
+import 'package:sharedinbox/ui/screens/edit_account_screen.dart';
 import 'package:sharedinbox/ui/screens/email_detail_screen.dart';
 import 'package:sharedinbox/ui/screens/email_list_screen.dart';
 import 'package:sharedinbox/ui/screens/mailbox_list_screen.dart';
@@ -47,6 +52,12 @@ class FakeAccountRepository implements AccountRepository {
   Future<void> addAccount(Account account, String password) async =>
       _accounts.add(account);
 
+  @override
+  Future<void> updateAccount(Account account, {String? password}) async {
+    final idx = _accounts.indexWhere((a) => a.id == account.id);
+    if (idx >= 0) _accounts[idx] = account;
+  }
+
   @override
   Future<void> removeAccount(String id) async =>
       _accounts.removeWhere((a) => a.id == id);
@@ -121,6 +132,28 @@ class FakeEmailRepository implements EmailRepository {
       _searchResults;
 }
 
+// ---------------------------------------------------------------------------
+// Fake services
+// ---------------------------------------------------------------------------
+
+class FakeDiscoveryService implements AccountDiscoveryService {
+  FakeDiscoveryService(this._result);
+  final DiscoveryResult _result;
+
+  @override
+  Future<DiscoveryResult> discover(String email) async => _result;
+}
+
+class FakeConnectionTestService implements ConnectionTestService {
+  FakeConnectionTestService({Exception? error}) : _error = error;
+  final Exception? _error;
+
+  @override
+  Future<void> testConnection(Account account, String password) async {
+    if (_error != null) throw _error;
+  }
+}
+
 // ---------------------------------------------------------------------------
 // App builder
 // ---------------------------------------------------------------------------
@@ -144,6 +177,12 @@ Widget buildApp({
             path: 'add',
             builder: (ctx, state) => const AddAccountScreen(),
           ),
+          GoRoute(
+            path: ':accountId/edit',
+            builder: (ctx, state) => EditAccountScreen(
+              accountId: state.pathParameters['accountId']!,
+            ),
+          ),
           GoRoute(
             path: ':accountId/mailboxes',
             builder: (ctx, state) => MailboxListScreen(
@@ -202,6 +241,29 @@ Widget buildApp({
   );
 }
 
+/// Convenience override list used by most widget tests.
+///
+/// Includes fakes for all repositories and the two network services so tests
+/// never hit the real database, network, or IMAP server.
+List<Override> baseOverrides({
+  List<Account>? accounts,
+  List<Mailbox>? mailboxes,
+  DiscoveryResult? discovery,
+  Exception? connectionError,
+}) =>
+    [
+      accountRepositoryProvider
+          .overrideWithValue(FakeAccountRepository(accounts)),
+      mailboxRepositoryProvider.overrideWithValue(FakeMailboxRepository(mailboxes)),
+      emailRepositoryProvider.overrideWithValue(FakeEmailRepository()),
+      accountDiscoveryServiceProvider.overrideWithValue(
+        FakeDiscoveryService(discovery ?? UnknownDiscovery()),
+      ),
+      connectionTestServiceProvider.overrideWithValue(
+        FakeConnectionTestService(error: connectionError),
+      ),
+    ];
+
 // ---------------------------------------------------------------------------
 // Common test fixtures
 // ---------------------------------------------------------------------------
@@ -211,11 +273,7 @@ const kTestAccount = Account(
   displayName: 'Alice',
   email: 'alice@example.com',
   imapHost: 'imap.example.com',
-  imapPort: 993,
-  imapSsl: true,
   smtpHost: 'smtp.example.com',
-  smtpPort: 587,
-  smtpSsl: false,
 );
 
 const kTestMailbox = Mailbox(