feat: deferred dispatch, release-check provider, settings polish

- Defer quiet-hours dispatches into new deferred_dispatch table; drain
  job + periodic catch-up scan re-fire at window end with coalescing on
  (link, event_type, collection_id).
- Add ON DELETE SET NULL migration on event_log_id and partial unique
  index on (link_id, collection_id, event_type) WHERE status='pending'.
- Add release-check provider abstraction (Gitea/GitHub) with SSRF-safe
  URL validation, settings UI cassette, and scheduled polling.
- Replace importlib-only version lookup with version.py helper that
  prefers the higher of installed metadata vs source pyproject so stale
  editable dev installs stop misreporting.
- Aurora frontend polish: MetaStrip component, ReleaseCassette,
  EventDetailModal expansion, and i18n additions.

packages/server/src/notify_bridge_server/main.py

@@ -76,6 +76,8 @@ async def lifespan(app: FastAPI):
         migrate_user_token_version,
         migrate_performance_indexes,
         migrate_chat_action_to_column,
+        migrate_deferred_dispatch_event_log_fk,
+        migrate_deferred_dispatch_unique_pending,
         migrate_schema_version,
     )
     from .database.snapshot import snapshot_and_prune
@@ -100,6 +102,11 @@ async def lifespan(app: FastAPI):
     await migrate_user_token_version(engine)
     await migrate_performance_indexes(engine)
     await migrate_chat_action_to_column(engine)
+    # FK-rebuild MUST run before the unique-index creation: drop+create_all
+    # of deferred_dispatch wipes its indexes; the next migration re-establishes
+    # the partial unique index.
+    await migrate_deferred_dispatch_event_log_fk(engine)
+    await migrate_deferred_dispatch_unique_pending(engine)
     await migrate_schema_version(engine)
     from .database.seeds import seed_all
     await seed_all()
@@ -147,11 +154,8 @@ async def lifespan(app: FastAPI):
     await dispose_engine()
 
 
-try:
-    from importlib.metadata import version as _pkg_version
-    _APP_VERSION = _pkg_version("notify-bridge-server")
-except Exception:  # pragma: no cover — editable install edge cases
-    _APP_VERSION = "0.0.0+unknown"
+from .version import resolve_version as _resolve_version
+_APP_VERSION = _resolve_version()
 
 app = FastAPI(title="Notify Bridge", version=_APP_VERSION, lifespan=lifespan)