Refactor auth and unify error handling in routers

Renamed AuthRequired/AdminRequired to auth_required/admin_required and updated all references. Replaced direct HTTPException usage with utils.http_exceptions for consistent error handling. Updated router endpoints to use new auth dependency and standardized not implemented responses. Cleaned up unused theme fields in SiteConfigResponse and improved site config endpoint. Minor type and import cleanups across routers and middleware.

routers/api/v1/directory/__init__.py

@@ -2,7 +2,7 @@ from typing import Annotated
 
 from fastapi import APIRouter, Depends, HTTPException
 
-from middleware.auth import AuthRequired
+from middleware.auth import auth_required
 from middleware.dependencies import SessionDep
 from models import (
     DirectoryCreateRequest,
@@ -26,7 +26,7 @@ directory_router = APIRouter(
 )
 async def router_directory_get(
         session: SessionDep,
-        user: Annotated[User, Depends(AuthRequired)],
+        user: Annotated[User, Depends(auth_required)],
         path: str
 ) -> DirectoryResponse:
     """
@@ -94,7 +94,7 @@ async def router_directory_get(
 )
 async def router_directory_create(
         session: SessionDep,
-        user: Annotated[User, Depends(AuthRequired)],
+        user: Annotated[User, Depends(auth_required)],
         request: DirectoryCreateRequest
 ) -> ResponseBase:
     """