fix: auto-fix code issues (cron)

- 修复PEP8格式问题（行长度超过120字符）
- 修复类型注解（添加__init__和_get_db返回类型）
- 删除__pycache__缓存文件
- 优化长SQL查询语句格式

backend/db_manager.py

@@ -167,7 +167,8 @@ class DatabaseManager:
     def create_entity(self, entity: Entity) -> Entity:
         conn = self.get_conn()
         conn.execute(
-            """INSERT INTO entities (id, project_id, name, canonical_name, type, definition, aliases, created_at, updated_at)
+            """INSERT INTO entities (id, project_id, name, canonical_name, type,
+               definition, aliases, created_at, updated_at)
                VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)""",
             (
                 entity.id,
@@ -736,7 +737,8 @@ class DatabaseManager:
         now = datetime.now().isoformat()
         conn.execute(
             """INSERT INTO attribute_templates
-               (id, project_id, name, type, options, default_value, description, is_required, sort_order, created_at, updated_at)
+               (id, project_id, name, type, options, default_value, description,
+                is_required, sort_order, created_at, updated_at)
                VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)""",
             (
                 template.id,