feat(storage): 添加 todos 表的 created_by_message_id 字段迁移

- 检查 todos 表中是否存在 created_by_message_id 列
- 若不存在则添加该列，类型为 TEXT
- 记录添加列的迁移过程日志
- 确保数据库表结构更新完成后返回成功状态

src/storage/mod.rs

@@ -1977,6 +1977,17 @@ fn ensure_todos_schema(conn: &Connection) -> Result<(), StorageError> {
         tracing::info!("Todos table migration complete");
     }
 
+    // Column migration: add created_by_message_id if it doesn't exist
+    let has_column = has_column(&conn, "todos", "created_by_message_id")?;
+    if !has_column {
+        tracing::info!("Adding created_by_message_id column to todos table");
+        conn.execute(
+            "ALTER TABLE todos ADD COLUMN created_by_message_id TEXT",
+            [],
+        )?;
+        tracing::info!("Todos table column migration complete");
+    }
+
     Ok(())
 }