feat(watch): clôture lot #91 - fréquence cardiaque live, notifications de séance et finitions montre

Consolide le lot applicatif watch companion validé :
- télémétrie fréquence cardiaque live remontée montre -> téléphone
  (collecteur watch, adapter Wear Data Layer, persistance Drift,
  propagation aux écrans historique/programme/profil/exécution)
- notifications de séance en arrière-plan côté téléphone (service
  foreground de statut + passerelle applicative)
- finitions montre : chrono d'étape, score d'étape, retrait du bouton
  "lancer une séance", thème, icônes et polices watch_app

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

test/infrastructure/remote/http_api_client_test.dart

@@ -0,0 +1,76 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:gametime/application/application.dart';
+import 'package:gametime/infrastructure/remote/remote.dart';
+import 'package:http/http.dart' as http;
+import 'package:http/testing.dart';
+
+void main() {
+  test(
+    'defaultBaseUrl keeps localhost outside Android without env override',
+    () {
+      expect(
+        HttpApiClient.defaultBaseUrlFor(isAndroid: false),
+        'http://localhost:8080',
+      );
+    },
+  );
+
+  test('defaultBaseUrl uses Android emulator host without env override', () {
+    expect(
+      HttpApiClient.defaultBaseUrlFor(isAndroid: true),
+      'http://10.0.2.2:8080',
+    );
+  });
+
+  test('defaultBaseUrl keeps env override on Android', () {
+    expect(
+      HttpApiClient.defaultBaseUrlFor(
+        isAndroid: true,
+        configuredBaseUrl: ' http://192.168.1.42:8080 ',
+      ),
+      'http://192.168.1.42:8080',
+    );
+  });
+
+  test('postJson maps server errors to server failure', () async {
+    final client = HttpApiClient(
+      baseUrl: Uri.parse('http://api.example.test'),
+      client: MockClient(
+        (_) async => http.Response('{"error":"internal"}', 500),
+      ),
+    );
+
+    await expectLater(
+      client.postJson('/auth/login'),
+      throwsA(
+        isA<RemoteAuthException>()
+            .having(
+              (error) => error.failure,
+              'failure',
+              RemoteAuthFailure.server,
+            )
+            .having((error) => error.message, 'message', 'internal'),
+      ),
+    );
+  });
+
+  test('postJson maps transport failures to network failure', () async {
+    final client = HttpApiClient(
+      baseUrl: Uri.parse('http://api.example.test'),
+      client: MockClient((_) async => throw http.ClientException('refused')),
+    );
+
+    await expectLater(
+      client.postJson('/auth/login'),
+      throwsA(
+        isA<RemoteAuthException>()
+            .having(
+              (error) => error.failure,
+              'failure',
+              RemoteAuthFailure.network,
+            )
+            .having((error) => error.message, 'message', 'refused'),
+      ),
+    );
+  });
+}