feat: v2.3.0 T1 — 站内信系统 (in-app notifications) (#307)

* feat: add in-app notification system (站内信) — schema, service, API, Bell UI

- Add `notifications` table to DB schema with userId/type/title/body/refType/refId/metadata/readAt/createdAt fields; two indexes for list & unread queries
- Migration `0010_notifications.sql` created manually (drizzle-kit requires TTY)
- Service layer: createNotification, listNotifications (paginated + unreadOnly filter), markAsRead (idempotent, owner-only), markAllAsRead, unreadCount
- REST API at `/api/notifications`: list + unreadCount, GET unread-count, POST :id/read (204), POST read-all
- Shared `Notification` type, `listNotificationsQuerySchema`, RPC client export
- NotificationBell (badge, 30s polling), NotificationDropdown, NotificationItem components injected into AppSidebar footer
- Bell badge capped at "9+"; unread items bold; click marks read + navigates via refType/refId
- i18n: en + zh translations for all notification keys
- 26 Node integration tests + 5 CF smoke tests; all 1884 + 26 tests pass

Agent-Profile: https://agent-kanban.dev/agents/a6bb038c4226a87f

* test: add notification API wrapper tests and component logic tests; fix dead condition

- Add tests for listNotifications, getUnreadCount, markNotificationRead, markAllNotificationsRead in api.test.ts
- Add notification-bell.test.ts: badge label logic (0/5/"9+" cap) and polling interval
- Add notification-dropdown.test.ts: mark-all-read visibility, empty state, query key
- Add notification-item.test.ts: resolveHref (share token nav, malformed JSON), diffMinutes, isUnread, title style
- Fix dead condition in markNotificationRead: simplify `!res.ok && res.status !== 204` → `!res.ok`

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* ci: trigger CI check run for test coverage fixes

---------

Co-authored-by: Bob <aibob@mails.agent-kanban.dev>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

server/test/setup.ts

@@ -193,6 +193,20 @@ const APP_SCHEMA_SQL = `
   );
   CREATE INDEX IF NOT EXISTS share_recipients_share_id_idx ON share_recipients(share_id);
   CREATE INDEX IF NOT EXISTS share_recipients_user_id_idx ON share_recipients(recipient_user_id);
+  CREATE TABLE IF NOT EXISTS notifications (
+    id TEXT PRIMARY KEY,
+    user_id TEXT NOT NULL,
+    type TEXT NOT NULL,
+    title TEXT NOT NULL,
+    body TEXT NOT NULL DEFAULT '',
+    ref_type TEXT,
+    ref_id TEXT,
+    metadata TEXT,
+    read_at INTEGER,
+    created_at INTEGER NOT NULL
+  );
+  CREATE INDEX IF NOT EXISTS notifications_user_created_idx ON notifications(user_id, created_at);
+  CREATE INDEX IF NOT EXISTS notifications_user_read_idx ON notifications(user_id, read_at);
 `
 
 export async function createTestApp() {