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/init_db.py

@@ -1,8 +1,8 @@
 #!/usr/bin/env python3
 """Initialize database with schema"""
 
-import sqlite3
 import os
+import sqlite3
 
 db_path = os.path.join(os.path.dirname(__file__), "insightflow.db")
 schema_path = os.path.join(os.path.dirname(__file__), "schema.sql")
@@ -11,7 +11,7 @@ print(f"Database path: {db_path}")
 print(f"Schema path: {schema_path}")
 
 # Read schema
-with open(schema_path, "r") as f:
+with open(schema_path) as f:
     schema = f.read()
 
 # Execute schema