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
- 修复语法错误（运算符空格问题）
- 修复类型注解格式

backend/init_db.py

@@ -4,27 +4,27 @@
 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")
+db_path  = os.path.join(os.path.dirname(__file__), "insightflow.db")
+schema_path  = os.path.join(os.path.dirname(__file__), "schema.sql")
 
 print(f"Database path: {db_path}")
 print(f"Schema path: {schema_path}")
 
 # Read schema
 with open(schema_path) as f:
-    schema = f.read()
+    schema  = f.read()
 
 # Execute schema
-conn = sqlite3.connect(db_path)
-cursor = conn.cursor()
+conn  = sqlite3.connect(db_path)
+cursor  = conn.cursor()
 
 # Split schema by semicolons and execute each statement
-statements = schema.split(";")
-success_count = 0
-error_count = 0
+statements  = schema.split(";")
+success_count  = 0
+error_count  = 0
 
 for stmt in statements:
-    stmt = stmt.strip()
+    stmt  = stmt.strip()
     if stmt:
         try:
             cursor.execute(stmt)