feat(ui): adopt Tailwind v4 design system and archive change

- Add tailwindcss v4 + @tailwindcss/vite to mall, shop-admin, admin
- Add @vmall/shared/theme.css tokens with html[data-accent] presets
- Add @vmall/ui kit (VBtn/VBadge/VField/VInput/VCard/VPanel/VTable/VPage,
  VAccentSwatch, useAccent) as a Nuxt module
- Convert all three apps to kit + utilities; delete ui.css/mall.css and
  every <style scoped>; consoles get accent presets, mall locked to red
- Fix VCard boolean prop default (padding) and PDP/store stale
  useAsyncData keys on param navigation
- Archive adopt-tailwind-design-system; new frontend-ui capability spec

apps/mall/components/ui/Tabs.vue

@@ -4,42 +4,19 @@ const emit = defineEmits<{ "update:modelValue": [key: string] }>();
 </script>
 
 <template>
-  <div class="tabs">
-    <div class="tab-head">
+  <div>
+    <div class="flex border-b border-border">
       <button
         v-for="tab in tabs"
         :key="tab.key"
         type="button"
-        :class="{ on: tab.key === modelValue }"
+        class="border-0 border-b-2 border-transparent bg-transparent px-6 py-3 text-sm text-muted transition-colors"
+        :class="tab.key === modelValue ? 'border-primary font-semibold text-primary' : 'hover:text-primary'"
         @click="emit('update:modelValue', tab.key)"
       >{{ tab.label }}</button>
     </div>
-    <div class="tab-body">
+    <div class="py-5">
       <slot :active="modelValue" />
     </div>
   </div>
 </template>
-
-<style scoped>
-.tab-head {
-  display: flex;
-  border-bottom: 1px solid var(--mall-line);
-}
-.tab-head button {
-  border: 0;
-  background: none;
-  padding: 12px 24px;
-  font-size: 14px;
-  cursor: pointer;
-  color: var(--mall-muted);
-  border-bottom: 2px solid transparent;
-}
-.tab-head button.on {
-  color: var(--mall-red);
-  border-bottom-color: var(--mall-red);
-  font-weight: 600;
-}
-.tab-body {
-  padding: 20px 0;
-}
-</style>