fix(tests): 修復 lint 錯誤 (I001, F401)

- test_smart_router.py: 移除未使用的 pytest import
- test_github_webhook.py: 修正 import 排序

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

apps/api/tests/test_github_webhook.py

@@ -16,17 +16,17 @@ import hmac
 import json
 import os
 
-import httpx
-import pytest
-from httpx import ASGITransport
-
 # 設定測試環境變數 (在 import main 之前)
 os.environ.setdefault("MOCK_MODE", "true")
 os.environ.setdefault("ENVIRONMENT", "dev")
 os.environ.setdefault("GITHUB_WEBHOOK_SECRET", "test-secret-key-12345")
 os.environ.setdefault("GITHUB_ALLOWED_REPOS", "test-owner/test-repo,wooo-ai/awoooi")
 
-from src.main import app  # noqa: E402
+import httpx
+import pytest
+from httpx import ASGITransport
+
+from src.main import app
 
 
 # =============================================================================

apps/api/tests/test_smart_router.py

@@ -4,8 +4,6 @@ Smart Router Tests - Phase 13.3
 測試意圖分類、複雜度評分、AI 路由
 """
 
-import pytest
-
 from src.services.intent_classifier import (
     IntentClassifier,
     IntentType,