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/vite.config.ts

@@ -3,6 +3,7 @@ import { defineConfig, loadEnv } from 'vite';
 import vue from '@vitejs/plugin-vue';
 import { VitePWA } from 'vite-plugin-pwa';
 import { $themeLessVars } from './themeConfig/themeConfig';
+import { lessAlphaPlugin, lightHex, palettePlugin } from './themeConfig/appearance';
 
 // Ports are defined once in the repo-root .env (USER_APP_PORT / API_PORT) —
 // see that file's comment block.
@@ -15,6 +16,8 @@ export default defineConfig({
   envDir: rootDir,
   plugins: [
     vue(),
+    // virtual:palette.css — the light/dark values behind the theme tokens.
+    palettePlugin(),
     // Ported from legacy vite.config.ts:18-52. Same injectManifest strategy,
     // same src/sw.ts entry, same manifest values (name/colors/icons/display).
     VitePWA({
@@ -29,8 +32,8 @@ export default defineConfig({
         name: 'Montzar',
         short_name: 'Montzar',
         description: 'Montzar',
-        theme_color: $themeLessVars.primary,
-        background_color: $themeLessVars.primary,
+        theme_color: lightHex.primary,
+        background_color: lightHex.primary,
         start_url: '/',
         display: 'standalone',
         icons: [
@@ -57,6 +60,8 @@ export default defineConfig({
       less: {
         modifyVars: $themeLessVars,
         javascriptEnabled: true,
+        // alpha(@token, N%) — fade() for theme tokens; see appearance.ts.
+        plugins: [lessAlphaPlugin],
       },
     },
   },