✨ feat(updater): 接入 GitHub Release 在线更新与关于信息展示

- 后端新增更新检查/下载/安装流程与应用信息接口
  - 关于弹窗展示版本/作者/仓库/Issue/Release，并内置检查更新
  - 构建/发布注入版本号并生成 SHA256SUMS
  - 顶部工具栏入口调整与新建查询补全默认空 SQL

frontend/src/components/Sidebar.tsx

@@ -979,7 +979,8 @@ const Sidebar: React.FC<{ onEditConnection?: (conn: SavedConnection) => void }>
                        title: `新建查询`,
                        type: 'query',
                        connectionId: node.key,
-                       dbName: undefined
+                       dbName: undefined,
+                       query: ''
                    });
                }
              },
@@ -1115,7 +1116,8 @@ const Sidebar: React.FC<{ onEditConnection?: (conn: SavedConnection) => void }>
                        title: `新建查询 (${node.title})`,
                        type: 'query',
                        connectionId: node.dataRef.id,
-                       dbName: node.title
+                       dbName: node.title,
+                       query: ''
                    });
                }
              },
@@ -1138,7 +1140,8 @@ const Sidebar: React.FC<{ onEditConnection?: (conn: SavedConnection) => void }>
                        title: `新建查询`,
                        type: 'query',
                        connectionId: node.dataRef.id,
-                       dbName: node.dataRef.dbName
+                       dbName: node.dataRef.dbName,
+                       query: ''
                    });
                 }
             },