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/components/ui/ToggleSwitch.vue

@@ -0,0 +1,59 @@
+<!--
+  The visual half of an on/off switch: a track and a knob. Deliberately not a
+  control on its own — the row that holds it is the <button role="switch">,
+  so the whole row is one tap target and screen readers announce one switch
+  (see views/user/AppearanceView.vue).
+
+  STRUCTURE IS SHARED, LOOK IS NOT: identical markup and script in user-app
+  and user-app-v2; only the "Look" block differs, per app.
+-->
+<template>
+  <span class="tsw" :class="{ 'is-on': on }" aria-hidden="true">
+    <span class="tsw__knob"></span>
+  </span>
+</template>
+
+<script setup lang="ts">
+defineProps<{ on: boolean }>()
+</script>
+
+<style scoped lang="less">
+/* ── Mechanics (same in both apps) ──────────────────────────── */
+.tsw {
+  position: relative;
+  flex: 0 0 auto;
+  display: inline-block;
+  width: 46px;
+  height: 28px;
+  border-radius: 999px;
+  transition: background-color 0.22s ease;
+}
+
+.tsw__knob {
+  position: absolute;
+  top: 3px;
+  // RTL page: "off" sits on the right (start), "on" slides to the left (end).
+  inset-inline-start: 3px;
+  width: 22px;
+  height: 22px;
+  border-radius: 50%;
+  box-shadow: 0 2px 6px -1px rgba(20, 22, 26, 0.35);
+  transition: transform 0.26s cubic-bezier(0.32, 0.72, 0, 1), background-color 0.22s ease;
+}
+
+.tsw.is-on .tsw__knob {
+  transform: translateX(-18px);
+}
+
+/* ── Look: user-app ─────────────────────────────────────────── */
+// The app's chosen state is brand green (@primary, as on chips and CTAs).
+.tsw {
+  background: @lightGray1;
+}
+.tsw__knob {
+  background: #fff;
+}
+.tsw.is-on {
+  background: @primary;
+}
+</style>