fix(api): 修復 ruff lint 錯誤

- langfuse_client.py: import Callable from collections.abc
- telemetry.py: import block 格式化

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/api/src/services/langfuse_client.py

@@ -36,7 +36,8 @@ Usage:
 
 from contextlib import asynccontextmanager
 from functools import wraps
-from typing import Any, Callable
+from collections.abc import Callable
+from typing import Any
 
 import structlog