feat(server): auth comptes utilisateurs et tokens API (ticket #48)

Ajoute la couche application (ports, use cases), les entités du
domaine, l'endpoint api/auth_api.dart (register/login/logout) et son
câblage dans le router, le hashing de mot de passe et le service de
token (infrastructure/security), et l'adapter Postgres des repositories
d'auth s'appuyant sur la table users du ticket #49. dart pub get OK,
dart analyze clean, dart test 10/10 vert (test PostgreSQL réel skip
faute de Docker disponible dans ce sandbox). Logique d'auth et
middleware testés via repositories fake en mémoire ; les endpoints
HTTP register/login/logout n'ont pas pu être exercés de bout en bout
faute d'accès à un vrai PostgreSQL local.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/bin/server.dart

@@ -1,12 +1,51 @@
 import 'dart:io';
 
+import 'package:gametime_server/api/auth_api.dart';
 import 'package:gametime_server/api/router.dart';
+import 'package:gametime_server/application/application.dart';
+import 'package:gametime_server/infrastructure/postgres/postgres.dart';
+import 'package:gametime_server/infrastructure/security/security.dart';
 import 'package:shelf/shelf_io.dart' as shelf_io;
 
 Future<void> main(List<String> arguments) async {
   final port = int.tryParse(Platform.environment['PORT'] ?? '') ?? 8080;
+  final connection = await PostgresConnectionFactory(
+    PostgresConnectionConfig.fromEnvironment(),
+  ).open();
+
+  final users = PostgresUserRepository(connection);
+  final sessions = PostgresAuthSessionRepository(connection);
+  final passwordHasher = Pbkdf2PasswordHasher();
+  final tokens = SecureOpaqueTokenService();
+  const clock = SystemClock();
+  final ids = UuidV4Generator();
+  final authenticateRequest = AuthenticateRequestUseCase(
+    users: users,
+    sessions: sessions,
+    tokens: tokens,
+    clock: clock,
+  );
+  final authApi = AuthApi(
+    registerUser: RegisterUserUseCase(
+      users: users,
+      passwordHasher: passwordHasher,
+      clock: clock,
+      ids: ids,
+    ),
+    login: LoginUseCase(
+      users: users,
+      sessions: sessions,
+      passwordHasher: passwordHasher,
+      tokens: tokens,
+      clock: clock,
+      ids: ids,
+    ),
+    logout: LogoutUseCase(sessions: sessions, tokens: tokens, clock: clock),
+    authenticateRequest: authenticateRequest,
+  );
+
   final server = await shelf_io.serve(
-    buildApiHandler(),
+    buildApiHandler(authApi: authApi),
     InternetAddress.anyIPv4,
     port,
   );