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/App.vue

@@ -21,10 +21,11 @@
 
     <DialogVantOneButton :timeOut="-1" v-model:show="versionDialog" :closeOnClickOverlay="true">
       <template v-slot:img>
+        <!-- Still (first frame) in reduced-motion mode. -->
         <DotLottieVue
           class="w-full aspect-square"
-          autoplay
-          loop
+          :autoplay="!appearance.isReducedMotion"
+          :loop="!appearance.isReducedMotion"
           src="https://lottie.host/cb620e8e-c64a-42e8-a6b5-8844146e5999/nmft7oBO8q.json"
         />
       </template>
@@ -34,10 +35,11 @@
       </template>
 
       <template v-slot:button>
-        <div class="text-center text-[#23493c]" @click="update()">به روز رسانی</div>
+        <div class="text-center text-[color:var(--c-primary)]" @click="update()">به روز رسانی</div>
       </template>
     </DialogVantOneButton>
 
+    <ProductMorph />
     <ToastHost />
   </div>
 </template>
@@ -51,10 +53,13 @@ import MasterLayout from './layout/MasterLayout.vue'
 import FullPageLayout from './layout/FullPageLayout.vue'
 import DialogVantOneButton from './components/DialogVantOneButton.vue'
 import ToastHost from './components/ui/ToastHost.vue'
+import ProductMorph from './components/product/ProductMorph.vue'
 import { useRefresh } from './composables/useRefresh'
+import { useAppearanceStore } from './stores/appearanceStore'
 import pkg from '../package.json'
 
 const router = useRouter()
+const appearance = useAppearanceStore()
 const { updateServiceWorker } = useRegisterSW()
 
 const getLayout = computed(() => {