登录注册：优化协议弹窗与PM后台落点

授权项目负责人登录后，若当前项目具备项目成员、中心管理或审计导出读取权限，优先进入对应管理后台页面，避免仍停留在我的工作台。

抽取登录协议为共享内容模块，注册页新增服务条款和隐私政策弹窗，并在注册成功后展示待管理员审核提示。

补充路由、登录页和注册页静态回归测试，覆盖 PM 管理后台默认落点和协议弹窗行为。

frontend/src/router/index.ts

@@ -472,6 +472,25 @@ const router = createRouter({
   routes,
 });
 
+const pmAdminLandingModules: Array<{ module: string; path: (studyId: string) => string }> = [
+  { module: "project_members", path: (studyId) => `/admin/projects/${studyId}/members` },
+  { module: "sites", path: (studyId) => `/admin/projects/${studyId}/sites` },
+  { module: "audit_export", path: () => "/admin/audit-logs" },
+];
+
+const findPmAdminLandingPath = async () => {
+  const studyStore = useStudyStore();
+  const studyId = studyStore.currentStudy?.id;
+  if (!studyId) return null;
+  if (!studyStore.currentPermissions) {
+    await studyStore.loadCurrentStudyPermissions();
+  }
+  const role = studyStore.currentStudyRole || (studyStore.currentStudy as any)?.role_in_study || "";
+  if (role !== "PM") return null;
+  const matched = pmAdminLandingModules.find((item) => !!studyStore.currentPermissions?.roles?.PM?.[item.module]?.read);
+  return matched ? matched.path(studyId) : null;
+};
+
 const ensureAdminProjectAccess = async (to: any, isAdmin: boolean) => {
   if (isAdmin) return true;
   const studyStore = useStudyStore();
@@ -530,13 +549,23 @@ router.beforeEach(async (to, _from, next) => {
     next({ path: studyStore.currentStudy ? "/project/overview" : "/admin/users" });
     return;
   }
+  if (!isAdmin && token && (to.path === "/" || to.path === "/workbench")) {
+    const pmAdminLanding = await findPmAdminLandingPath().catch(() => null);
+    if (pmAdminLanding) {
+      next({ path: pmAdminLanding });
+      return;
+    }
+  }
   if ((to.path === "/login" || to.path === "/register") && token) {
     if (!auth.forceLogin) {
+      const pmAdminLanding = isAdmin ? null : await findPmAdminLandingPath().catch(() => null);
       next({
         path: isAdmin
           ? studyStore.currentStudy
             ? "/project/overview"
             : "/admin/users"
+          : pmAdminLanding
+            ? pmAdminLanding
           : studyStore.currentStudy
             ? "/project/overview"
             : "/workbench",