feat: add admin usage statistics and LLM configuration management

qwen3-tts-backend/api/admin.py

@@ -0,0 +1,22 @@
+from datetime import datetime
+from typing import Optional
+
+from fastapi import APIRouter, Depends, Query
+from sqlalchemy.orm import Session
+
+from api.users import require_superuser
+from db.database import get_db
+from db.crud import get_usage_stats
+from schemas.user import User
+
+router = APIRouter(prefix="/admin", tags=["admin"])
+
+
+@router.get("/usage")
+async def get_usage_statistics(
+    date_from: Optional[datetime] = Query(None),
+    date_to: Optional[datetime] = Query(None),
+    db: Session = Depends(get_db),
+    _: User = Depends(require_superuser),
+):
+    return get_usage_stats(db, date_from=date_from, date_to=date_to)