feat: 删除 admin 会议全览菜单 + 死页面 admin/Meetings.vue

admin 账号不关注会议, 移除 admin 视角的会议入口。

清理:
- router L29: 删除 admin-meetings 路由
- AdminLayout L78: 删除「会议全览」菜单项
- 删除 ry-vue3/src/views/admin/Meetings.vue (~95 行死页面, 同 admin/Projects.vue 一样是早期未完成桩)

Calendar icon 仍由 leader/manager/doctor/executor/sponsor 角色使用, 保留 import。

ry-vue3/src/router/index.js

@@ -26,7 +26,6 @@ const routes = [
       { path: 'users', name: 'admin-users', component: () => import('@/views/admin/Users.vue'), meta: { title: '用户管理' } },
       { path: 'roles', name: 'admin-roles', component: () => import('@/views/admin/Roles.vue'), meta: { title: '角色管理' } },
       { path: 'projects', name: 'admin-projects', component: () => import('@/views/manager/Projects.vue'), meta: { title: '项目管理' } },
-      { path: 'meetings', name: 'admin-meetings', component: () => import('@/views/admin/Meetings.vue'), meta: { title: '会议全览' } },
       { path: 'department', name: 'admin-department', component: () => import('@/views/admin/Department.vue'), meta: { title: '科室管理' } },
       { path: 'title', name: 'admin-title', component: () => import('@/views/admin/Title.vue'), meta: { title: '职称管理' } },
       { path: 'experts', name: 'admin-experts', component: () => import('@/views/expert/Experts.vue'), meta: { title: '专家管理' } },