feat(bibliothèque): migration Drift v16, seed basket et seeding au démarrage (ticket #80)

Ajoute la migration Drift v16 (enum ExerciseCategory, champ isExample sur
exercises/programs/workout_templates, table local_seed_metadata), le
contenu seed basket déterministe (21 exercices, 1 programme, 1 séance-
modèle) dans lib/application/starter_content/, les ports
StarterSeedStateRepository/StarterContentRepository et le use case
SeedStarterContentUseCase branché dans AppBootstrap.create().

Validé GO par QA/Main : dart analyze propre, suite complète 167 tests
(4 échecs préexistants sans rapport avec ce lot), 4 nouveaux tests seed
tous verts.

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

lib/application/app_bootstrap.dart

@@ -68,6 +68,7 @@ final class AppBootstrap implements AppDependencies {
     final syncMetadataRepository = DriftSyncMetadataRepository(database);
     final mappingRepository = DriftRemoteResourceMappingRepository(database);
     final localSyncChangeRepository = DriftLocalSyncChangeRepository(database);
+    final starterSeedRepository = DriftStarterSeedRepository(database);
     final shareInboxRepository = DriftShareInboxRepository(database);
     final pendingShareActionRepository = DriftPendingShareActionRepository(
       database,
@@ -79,6 +80,12 @@ final class AppBootstrap implements AppDependencies {
     final ids = LocalIdGenerator();
     const clock = SystemClock();
     const originDeviceId = 'local-device';
+    await SeedStarterContentUseCase(
+      seedStateRepository: starterSeedRepository,
+      contentRepository: starterSeedRepository,
+      clock: clock,
+      originDeviceId: originDeviceId,
+    ).run();
     final remoteAuthApi = HttpRemoteAuthApi(
       HttpApiClient(baseUrl: Uri.parse(HttpApiClient.defaultBaseUrl)),
     );