feat: production-harden app and finalize merge-ready UX/theme baseline

- complete tokenized theme preset system and admin style guide visibility
- refine dashboard layout/scroll behavior and shared async/request UI states
- add user nav-visibility settings across API, migration, and frontend stores
- harden security headers/CSP handling and related test coverage
- enforce CI repository hygiene + frontend contract/theme/build quality gates
- update docs/env references and make migration smoke test head-aware

frontend/src/components/ui/AppEmptyState.vue

@@ -6,9 +6,9 @@ defineProps<{
 </script>
 
 <template>
-  <section class="rounded-xl border border-dashed border-zinc-300 bg-zinc-50 p-5 dark:border-zinc-700 dark:bg-zinc-900/60">
-    <h3 class="font-display text-lg font-semibold text-zinc-900 dark:text-zinc-100">{{ title }}</h3>
-    <p class="mt-1 text-sm text-zinc-600 dark:text-zinc-400">{{ body }}</p>
+  <section class="rounded-xl border border-dashed border-stroke-interactive bg-surface-card-muted p-5">
+    <h3 class="font-display text-lg font-semibold text-ink-primary">{{ title }}</h3>
+    <p class="mt-1 text-sm text-ink-secondary">{{ body }}</p>
     <div v-if="$slots.default" class="mt-4">
       <slot />
     </div>