Add local bearer authentication foundation

SovereignAI-Starter/flutter_app/lib/core/network/api_repository.dart

@@ -21,8 +21,8 @@ class ApiRepository {
   ApiRepository({required String baseUrl}) : _baseUrl = baseUrl;
 
   String _baseUrl;
-  String? _cachedUserId;
-  Future<String>? _loadingUserId;
+  String? _accessToken;
+  Future<String>? _loadingLocalSession;
   http.Client? _activeRequestClient;
   String get baseUrl => _baseUrl;
 
@@ -33,8 +33,11 @@ class ApiRepository {
 
   String newId() => _uuid.v4();
 
-  void setBaseUrl(String value) =>
-      _baseUrl = value.replaceFirst(RegExp(r'/+$'), '');
+  void setBaseUrl(String value) {
+    _baseUrl = value.replaceFirst(RegExp(r'/+$'), '');
+    _accessToken = null;
+    _loadingLocalSession = null;
+  }
 
   Future<String> getModelName() async {
     final response = await http.get(Uri.parse('$_baseUrl/health'));
@@ -60,25 +63,75 @@ class ApiRepository {
     }).toList();
   }
 
-  Future<String> _userId() async {
-    final cached = _cachedUserId;
+  Future<String> _localSessionToken() async {
+    final cached = _accessToken;
     if (cached != null) return cached;
-    return _loadingUserId ??= _loadLocalUserId();
+    final existing = _loadingLocalSession;
+    if (existing != null) return existing;
+    final pending = _loadLocalSessionToken();
+    _loadingLocalSession = pending;
+    try {
+      return await pending;
+    } finally {
+      _loadingLocalSession = null;
+    }
   }
 
-  Future<String> _loadLocalUserId() async {
-    final response = await http.get(Uri.parse('$_baseUrl/v1/local-user'));
+  Future<String> _loadLocalSessionToken() async {
+    final response = await http.post(
+      Uri.parse('$_baseUrl/v1/auth/local-session'),
+      headers: const {'Content-Type': 'application/json'},
+      body: '{}',
+    );
     _checkStatus(response);
     final data = jsonDecode(response.body) as Map<String, dynamic>;
-    _cachedUserId = data['user_id'] as String;
-    return _cachedUserId!;
+    _accessToken = data['access_token'] as String;
+    return _accessToken!;
   }
 
   Future<Map<String, String>> _userHeaders() async => {
     'Content-Type': 'application/json',
-    'X-User-ID': await _userId(),
+    'Authorization': 'Bearer ${await _localSessionToken()}',
   };
 
+  Future<Map<String, dynamic>> registerAccount({
+    required String email,
+    required String password,
+  }) => _authenticateAccount('register', email, password);
+
+  Future<Map<String, dynamic>> login({
+    required String email,
+    required String password,
+  }) => _authenticateAccount('login', email, password);
+
+  Future<Map<String, dynamic>> _authenticateAccount(
+    String action,
+    String email,
+    String password,
+  ) async {
+    final response = await http.post(
+      Uri.parse('$_baseUrl/v1/auth/$action'),
+      headers: const {'Content-Type': 'application/json'},
+      body: jsonEncode({'email': email, 'password': password}),
+    );
+    _checkStatus(response);
+    final data = jsonDecode(response.body) as Map<String, dynamic>;
+    _accessToken = data['access_token'] as String;
+    return data;
+  }
+
+  Future<void> logout() async {
+    final token = _accessToken;
+    if (token == null) return;
+    final response = await http.post(
+      Uri.parse('$_baseUrl/v1/auth/logout'),
+      headers: {'Authorization': 'Bearer $token'},
+    );
+    _checkStatus(response);
+    _accessToken = null;
+    _loadingLocalSession = null;
+  }
+
   void _checkStatus(http.Response response) {
     if (response.statusCode < 200 || response.statusCode >= 300) {
       throw Exception(_apiError(response));