feat: Enhance file management and user features

- Add file deduplication mechanism based on PhysicalFile reference counting.
- Implement chunked upload support for large files with resumable uploads.
- Update sharing page to automatically render README and preview content.
- Integrate Redis for caching and token storage (optional).
- Refactor project structure to include new models for download tasks, nodes, and tasks.
- Introduce user filtering parameters for admin user management.
- Add CORS middleware for handling cross-origin requests.
- Improve error messages for authentication failures.
- Update user model to include two-factor authentication key management.
- Enhance API documentation and response models for clarity.
- Implement admin checks for user management and permissions.

routers/api/v1/admin/__init__.py

@@ -1,6 +1,6 @@
 from datetime import datetime, timedelta
 
-from fastapi import APIRouter, Depends
+from fastapi import APIRouter, Depends, status
 from loguru import logger as l
 from sqlalchemy import and_
 
@@ -56,6 +56,23 @@ admin_aria2_router = APIRouter(
     tags=['admin', 'admin_aria2']
 )
 
+@admin_router.get(
+    path='/',
+    summary='自己是否为管理员',
+    dependencies=[Depends(admin_required)],
+    status_code=status.HTTP_204_NO_CONTENT
+)
+async def is_admin() -> None:
+    """
+    检查当前用户是否具有管理员权限。
+
+    如果用户是管理员，则返回 204 No Content 响应；否则返回 403 Forbidden 错误。
+
+    Returns:
+        None: 无内容响应
+    """
+    return None
+
 @admin_router.get(
     path='/summary',
     summary='获取站点概况',