refactor: 数据源菜单合一+布局优化

- 4个数据源菜单(MySQL/PG/Redis/Mongo)合并为1个「数据源」
- InstancePage 改为统一入口，顶部Tab切换类型过滤
- 添加数据源改为弹框Modal（默认MySQL）
- 去掉左下角用户区，退出登录移到右上角header
- 侧边栏收窄220px，整体布局更紧凑
- 后端202 tests passing
- 前端构建零错误

frontend/src/api/redis.ts

@@ -0,0 +1,37 @@
+import request from './request';
+
+export var redisApi = {
+  getInfo: function (id: number) {
+    return request.get('/redis/' + id + '/info');
+  },
+  getDbsize: function (id: number, db: number) {
+    return request.get('/redis/' + id + '/dbsize', { params: { db: db } });
+  },
+  getKeys: function (id: number, params: Record<string, any>) {
+    return request.get('/redis/' + id + '/keys', { params: params });
+  },
+  getKeyDetail: function (id: number, key: string, db: number) {
+    return request.get('/redis/' + id + '/keys/' + encodeURIComponent(key), { params: { db: db } });
+  },
+  createKey: function (id: number, data: Record<string, any>) {
+    return request.post('/redis/' + id + '/keys', data);
+  },
+  deleteKey: function (id: number, key: string, db: number) {
+    return request.delete('/redis/' + id + '/keys/' + encodeURIComponent(key), { params: { db: db } });
+  },
+  setExpire: function (id: number, key: string, data: Record<string, any>) {
+    return request.put('/redis/' + id + '/keys/' + encodeURIComponent(key) + '/expire', data);
+  },
+  flushDb: function (id: number, db: number) {
+    return request.delete('/redis/' + id + '/flushdb', { params: { db: db } });
+  },
+  executeCommand: function (id: number, data: Record<string, any>) {
+    return request.post('/redis/' + id + '/command', data);
+  },
+  getSlowlog: function (id: number, count: number) {
+    return request.get('/redis/' + id + '/slowlog', { params: { count: count } });
+  },
+  getClients: function (id: number) {
+    return request.get('/redis/' + id + '/clients');
+  },
+};