feat: 新增管理端工作台总览

- 新增 Dashboard 统计接口、菜单迁移与权限点

- 管理端工作台页面切换为真实概览数据和趋势图

- 默认首页切换到工作台

easyflow-starter/easyflow-starter-all/src/main/resources/db/migration/V5__dashboard_workspace_menu.sql

@@ -0,0 +1,39 @@
+SET NAMES utf8mb4;
+
+INSERT INTO `tb_sys_menu` (
+  `id`, `parent_id`, `menu_type`, `menu_title`, `menu_url`, `component`, `menu_icon`,
+  `is_show`, `permission_tag`, `sort_no`, `status`, `created`, `created_by`, `modified`, `modified_by`, `remark`
+) VALUES (
+  366200000000000001, 0, 0, 'menus.dashboard.workspace', '/dashboard/workspace', '/dashboard/workspace/index',
+  'carbon:workspace', 1, '', 1, 0, '2026-03-24 10:00:00', 1, '2026-03-24 10:00:00', 1, '管理员工作台'
+);
+
+INSERT INTO `tb_sys_menu` (
+  `id`, `parent_id`, `menu_type`, `menu_title`, `menu_url`, `component`, `menu_icon`,
+  `is_show`, `permission_tag`, `sort_no`, `status`, `created`, `created_by`, `modified`, `modified_by`, `remark`
+) VALUES (
+  366200000000000002, 366200000000000001, 1, '查询', '', '', '',
+  0, '/api/v1/dashboard/query', 1, 0, '2026-03-24 10:00:00', 1, '2026-03-24 10:00:00', 1, '工作台统计查询权限'
+);
+
+INSERT INTO `tb_sys_role_menu` (`id`, `role_id`, `menu_id`)
+SELECT
+  CASE r.role_key
+    WHEN 'super_admin' THEN 366200000000000101
+    WHEN 'tenant_admin' THEN 366200000000000102
+  END AS `id`,
+  r.id AS `role_id`,
+  366200000000000001 AS `menu_id`
+FROM `tb_sys_role` r
+WHERE r.role_key IN ('super_admin', 'tenant_admin');
+
+INSERT INTO `tb_sys_role_menu` (`id`, `role_id`, `menu_id`)
+SELECT
+  CASE r.role_key
+    WHEN 'super_admin' THEN 366200000000000103
+    WHEN 'tenant_admin' THEN 366200000000000104
+  END AS `id`,
+  r.id AS `role_id`,
+  366200000000000002 AS `menu_id`
+FROM `tb_sys_role` r
+WHERE r.role_key IN ('super_admin', 'tenant_admin');