refactor(ui): replace modal dialogs with toast/sheet components

Remove DialogVant/NotifyVant and add Toast and Sheet components with
useToast, useReveal, and usePageTransition composables. Rework
Navigation, RegisterView, and styles across both apps; rebuild dist assets.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/user-app/src/router/index.ts

@@ -3,6 +3,7 @@ import { useSessionStore } from '../stores/session';
 import { useNavStore } from '../stores/navStore';
 import { useTransitionStore } from '../stores/transitionStore';
 import { api } from '../api/client';
+import { afterPageLeave } from '../composables/usePageTransition';
 
 // Legacy lazy-loaded every route component (`component: () => import(...)`) so
 // the initial bundle only carries the entry route. Matched here.
@@ -10,7 +11,11 @@ export const router = createRouter({
   history: createWebHistory(),
   // Ported from legacy router/index.ts:225-237 — restore saved scroll on
   // back/forward, otherwise jump to top on every navigation.
-  scrollBehavior(_to, _from, savedPosition) {
+  // Waits for MasterLayout's outgoing page to finish fading first, so the
+  // scroll happens behind the still-transparent incoming page instead of
+  // jerking the old one to the top mid-fade (see composables/usePageTransition.ts).
+  async scrollBehavior(_to, _from, savedPosition) {
+    await afterPageLeave();
     if (savedPosition) return savedPosition;
     return { top: 0 };
   },