feat(v4.1.0): 文本类别添加待办事务功能

- 可在文本数据详情中追加待办事务
- 支持事务内容、剩余天数（默认1天）、完成状态
- 历史事务按时间倒序排列，显示创建/更新时间
- 分页显示，每页10条

xian_favor/db.py

@@ -187,6 +187,22 @@ class Database:
             cursor.execute("CREATE INDEX IF NOT EXISTS idx_folders_type ON folders(type)")
             cursor.execute("CREATE INDEX IF NOT EXISTS idx_folders_parent ON folders(parent_id)")
             
+            # 待办事务表（关联到文本类别的items）
+            cursor.execute("""
+                CREATE TABLE IF NOT EXISTS todo_events (
+                    id INTEGER PRIMARY KEY AUTOINCREMENT,
+                    item_id INTEGER NOT NULL,
+                    content TEXT NOT NULL,
+                    remaining_days INTEGER DEFAULT 1,
+                    is_completed INTEGER DEFAULT 0,
+                    created_at TEXT NOT NULL,
+                    updated_at TEXT NOT NULL,
+                    FOREIGN KEY (item_id) REFERENCES items(id) ON DELETE CASCADE
+                )
+            """)
+            cursor.execute("CREATE INDEX IF NOT EXISTS idx_todo_events_item ON todo_events(item_id)")
+            cursor.execute("CREATE INDEX IF NOT EXISTS idx_todo_events_created ON todo_events(created_at)")
+            
             conn.commit()
     
     # ============ Item 操作 ============
@@ -1166,6 +1182,93 @@ class Database:
                 # 删除
                 self.delete_backup(backup['name'])
 
+    # ============ Todo Events 待办事务操作 ============
+    
+    def create_todo_event(self, item_id: int, content: str, remaining_days: int = 1) -> int:
+        """创建待办事务"""
+        self._ensure_init()
+        now = datetime.now().isoformat()
+        
+        with self.get_conn() as conn:
+            cursor = conn.cursor()
+            cursor.execute("""
+                INSERT INTO todo_events (item_id, content, remaining_days, is_completed, created_at, updated_at)
+                VALUES (?, ?, ?, 0, ?, ?)
+            """, (item_id, content, remaining_days, now, now))
+            conn.commit()
+            return cursor.lastrowid
+    
+    def list_todo_events(self, item_id: int, limit: int = 10, offset: int = 0) -> List[Dict[str, Any]]:
+        """列出待办事务（按时间倒序）"""
+        self._ensure_init()
+        
+        with self.get_conn() as conn:
+            cursor = conn.cursor()
+            cursor.execute("""
+                SELECT * FROM todo_events 
+                WHERE item_id = ? 
+                ORDER BY created_at DESC 
+                LIMIT ? OFFSET ?
+            """, (item_id, limit, offset))
+            rows = cursor.fetchall()
+            return [dict(row) for row in rows]
+    
+    def count_todo_events(self, item_id: int) -> int:
+        """计算待办事务总数"""
+        self._ensure_init()
+        
+        with self.get_conn() as conn:
+            cursor = conn.cursor()
+            cursor.execute("SELECT COUNT(*) as count FROM todo_events WHERE item_id = ?", (item_id,))
+            return cursor.fetchone()['count']
+    
+    def get_todo_event(self, event_id: int) -> Optional[Dict[str, Any]]:
+        """获取单个待办事务"""
+        self._ensure_init()
+        
+        with self.get_conn() as conn:
+            cursor = conn.cursor()
+            cursor.execute("SELECT * FROM todo_events WHERE id = ?", (event_id,))
+            row = cursor.fetchone()
+            return dict(row) if row else None
+    
+    def update_todo_event(self, event_id: int, content: str = None, remaining_days: int = None, is_completed: bool = None) -> bool:
+        """更新待办事务"""
+        self._ensure_init()
+        now = datetime.now().isoformat()
+        
+        with self.get_conn() as conn:
+            cursor = conn.cursor()
+            
+            # 获取当前数据
+            cursor.execute("SELECT * FROM todo_events WHERE id = ?", (event_id,))
+            row = cursor.fetchone()
+            if not row:
+                return False
+            
+            # 更新字段
+            new_content = content if content is not None else row['content']
+            new_days = remaining_days if remaining_days is not None else row['remaining_days']
+            new_completed = 1 if is_completed is True else (0 if is_completed is False else row['is_completed'])
+            
+            cursor.execute("""
+                UPDATE todo_events 
+                SET content = ?, remaining_days = ?, is_completed = ?, updated_at = ?
+                WHERE id = ?
+            """, (new_content, new_days, new_completed, now, event_id))
+            conn.commit()
+            return True
+    
+    def delete_todo_event(self, event_id: int) -> bool:
+        """删除待办事务"""
+        self._ensure_init()
+        
+        with self.get_conn() as conn:
+            cursor = conn.cursor()
+            cursor.execute("DELETE FROM todo_events WHERE id = ?", (event_id,))
+            conn.commit()
+            return cursor.rowcount > 0
+
 
 # 全局数据库实例
 db = Database()