refactor(meetings): MeetingNew admin/manager 双前缀路由 (admin 不用 /manager 路径)

把 'admin 用 manager 前缀 URL' 这个跨角色硬编码改对称.

router:
- 新增 admin-meetings-new → manager/MeetingNew.vue (公共页)

MeetingNew.vue goBack():
- new 模式: admin 跳 /admin/projects, manager 跳 /manager/projects (用 projectsBase computed)
- edit/copy 模式: admin 跳 /admin/meetings, manager 跳 /manager/meetings (用 meetingsBase computed)
- roleSegment / isAdmin 从 route.path.split('/')[1] 计算, 不依赖 userStore

meetings/Meetings.vue onEdit/onCopy:
- 引入 newRouteName computed (isAdmin ? 'admin-meetings-new' : 'manager-meetings-new')
- router.push({ name: newRouteName.value, query: {...} })

效果:
- admin 点 '新建/修改/复制' → URL 是 /admin/meetings/new, 不再跨到 /manager/meetings/new
- admin 取消保存 → 回 /admin/meetings (列表) 或 /admin/projects (新建上游)
- manager 行为不变

ry-vue3/src/router/index.js

@@ -28,6 +28,7 @@ const routes = [
       { 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/meetings/Meetings.vue'), meta: { title: '会议管理' } },
       { path: 'meetings/detail/:meetingId', name: 'admin-meetings-detail', component: () => import('@/views/manager/MeetingDetail.vue'), meta: { title: '会议详情' } },
+      { path: 'meetings/new', name: 'admin-meetings-new', component: () => import('@/views/manager/MeetingNew.vue'), meta: { title: '新建会议' } },
       { 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' } },