功能(提醒)：统一项目提醒中心与桌面通知链路

增加通用提醒状态、数据库迁移和定时同步，覆盖风险时效、文件回执、项目里程碑、访视窗口与协作申请。

新增网页端和桌面端提醒中心、真实投递诊断与固定隐私通知正文，并补齐登录来源聚合、测试和说明文档。

backend/app/api/v1/notifications.py

@@ -1,4 +1,3 @@
-import logging
 import uuid
 
 from fastapi import APIRouter, Depends, Response, status
@@ -9,7 +8,6 @@ from app.schemas.notification import GeneralNotificationFeed, GeneralNotificatio
 from app.services import document_service, notification_service, project_reminder_service
 
 router = APIRouter()
-logger = logging.getLogger(__name__)
 
 
 @router.get(
@@ -40,20 +38,25 @@ async def list_notifications(
 )
 async def list_general_notifications(
     study_id: uuid.UUID,
+    skip: int = 0,
     limit: int = 10,
+    category: str | None = None,
+    unread_only: bool = False,
+    requires_action: bool | None = None,
     db: AsyncSession = Depends(get_db_session),
     current_user=Depends(get_current_user),
 ) -> GeneralNotificationFeed:
-    try:
-        await project_reminder_service.sync_project_reminders(db, study_id, current_user)
-    except Exception:
-        await db.rollback()
-        logger.warning("Failed to synchronize legacy project reminders", exc_info=True)
+    # Fail closed: stale reminders may contain details for a permission that was just revoked.
+    await project_reminder_service.sync_project_reminders(db, study_id, current_user)
     return await notification_service.list_feed(
         db,
         study_id=study_id,
         recipient_id=current_user.id,
+        skip=skip,
         limit=limit,
+        category=category,
+        unread_only=unread_only,
+        requires_action=requires_action,
     )