Add ntfy notification for super admin login

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

backend/app/routers/admin.py

@@ -9,6 +9,7 @@ from app.auth.jwt import create_admin_token, create_access_token, hash_password
 from app.config import get_settings
 from app.dependencies import get_db, get_admin_user
 from app.models.user import User
+from app.utils.ntfy import notify
 
 router = APIRouter(prefix="/api/admin", tags=["admin"])
 settings = get_settings()
@@ -22,6 +23,12 @@ async def admin_login(body: dict):
         logger.warning("Failed super-admin login attempt for username=%s", username)
         raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid admin credentials")
     token = create_admin_token({"sub": "admin"})
+    await notify(
+        title="Super Admin Login",
+        message=f"Admin logged in as: {username}",
+        priority="high",
+        tags=["key"],
+    )
     return {"access_token": token, "token_type": "bearer"}