fix: auto-fix code issues (cron)

- 修复重复导入/字段
- 修复异常处理
- 修复PEP8格式问题
- 添加类型注解

backend/api_key_manager.py

@@ -15,11 +15,13 @@ from enum import Enum
 
 DB_PATH = os.getenv("DB_PATH", "/app/data/insightflow.db")
 
+
 class ApiKeyStatus(Enum):
     ACTIVE = "active"
     REVOKED = "revoked"
     EXPIRED = "expired"
 
+
 @dataclass
 class ApiKey:
     id: str
@@ -37,6 +39,7 @@ class ApiKey:
     revoked_reason: str | None
     total_calls: int = 0
 
+
 class ApiKeyManager:
     """API Key 管理器"""
 
@@ -522,9 +525,11 @@ class ApiKeyManager:
             total_calls=row["total_calls"],
         )
 
+
 # 全局实例
 _api_key_manager: ApiKeyManager | None = None
 
+
 def get_api_key_manager() -> ApiKeyManager:
     """获取 API Key 管理器实例"""
     global _api_key_manager