feat(user-apps): appearance settings (dark mode + reduced motion), product morph, filter sheet

Applies to both user-app and user-app-v2. Logic and structure are shared;
each app keeps its own look.

Appearance settings
- New "تنظیمات ظاهری" page (/settings/appearance), opened from the
  dashboard and available without login. It offers a light/dark/system
  theme and a "fast & light" motion switch.
- appearanceStore saves the choice to localStorage. A small inline boot
  script in index.html applies it before first paint so there is no
  white flash. The "system" option follows OS changes live.
- New ToggleSwitch component.

Dark mode
- Theme LESS tokens now compile to CSS custom properties. Light/dark
  values come from a generated virtual:palette.css (themeConfig/
  appearance.ts, with colors.json + new colors.dark.json).
- New LESS alpha() plugin replaces fade() on theme tokens.
- New semantic tokens: page, onInk, heroSurface, hairlineStrong,
  photoMat, photoStage.
- The dark palette is layered (page < card < panel < border) so
  surfaces separate without shadows.
- Hard-coded colors were replaced by tokens according to their role.
- antd inputs/text get dark overrides; vant uses its own
  .van-theme-dark.
- Light mode looks the same as before.

Reduced motion
- With html.motion-reduced, transitions are capped at 120ms, keyframe
  loops stop, and backdrop blurs and permanent will-change are dropped.
- Spinners and the toast progress bar (which closes the toast) are
  exempt via .keep-motion.
- Carousel autoplay, the v1 Lottie and the product morph honor the
  setting.

Product detail
- Opening a product is now a container-transform morph from the tapped
  card (ProductMorph). It replaces the bottom Drawer and uses composited
  transform/opacity only.
- The detail view is seeded with the card's data, so it no longer
  opens blank and jumps.

Filters and sheets
- Filters are now a full-width bottom sheet. Selections stay a draft
  until applied, so the result list no longer re-renders while
  dragging the slider.
- DropDown collapse animates grid-template-rows instead of a capped
  max-height.
- v2 IslandSheet is restyled to the v2 design language (API unchanged).

Fixes
- filtersStore.reset() shallow-copied shared arrays, so clearing the
  filters never cleared the selected brands.

apps/user-app/src/main.ts

@@ -5,6 +5,7 @@ import App from './App.vue';
 import { router } from './router';
 import { setUnauthorizedHandler } from './api/client';
 import { useSessionStore } from './stores/session';
+import { useAppearanceStore } from './stores/appearanceStore';
 import Container from './components/ui/Container.vue';
 // TODO: temporary placeholder — swap Vector.svg back in (or a proper loading
 // mark) once one exists; montzar-logo.png is the brand logo, borrowed here
@@ -14,6 +15,9 @@ import Vector from './assets/img/montzar-logo.png';
 // Global styles, ported from legacy henza_pwa/src/main.ts — same import order
 // (ant-design-vue's own theme first, then our Less overrides on top). Legacy
 // imported 'vant/lib/index.css' twice (a dead duplicate) — imported once here.
+// The light/dark values behind the theme tokens — first, so every stylesheet
+// below resolves var(--c-…) against it. See themeConfig/appearance.ts.
+import 'virtual:palette.css';
 import './assets/styles/tailwind.css';
 import 'ant-design-vue/dist/antd.less';
 import './assets/styles/style.less';
@@ -22,6 +26,9 @@ import 'vant/lib/index.css';
 const app = createApp(App);
 
 app.use(createPinia());
+// Theme + reduced motion. index.html already applied the saved classes before
+// first paint; this keeps them in sync (and follows the OS while on "system").
+useAppearanceStore().init();
 app.use(router);
 
 // A 401 from the API means the customer token is gone or expired. Clear the