feat: 标签管理添加编辑功能，支持修改标签名称

xian_favor/db.py

@@ -244,6 +244,18 @@ class Database:
             """)
             return [dict(row) for row in cursor.fetchall()]
     
+    def update_tag(self, tag_id: int, name: str) -> bool:
+        """更新标签名称"""
+        with self.get_conn() as conn:
+            cursor = conn.cursor()
+            # 检查名称是否已存在（排除自己）
+            cursor.execute("SELECT id FROM tags WHERE name = ? AND id != ?", (name, tag_id))
+            if cursor.fetchone():
+                return False  # 名称已存在
+            cursor.execute("UPDATE tags SET name = ? WHERE id = ?", (name, tag_id))
+            conn.commit()
+            return cursor.rowcount > 0
+    
     def delete_tag(self, tag_id: int = None, name: str = None) -> bool:
         """删除标签"""
         with self.get_conn() as conn: