Vendor Chatwoot Vue 3 frontend into frontend/

Copy the Chatwoot (v4.14.0) frontend runnable subset into frontend/ for
customization:
- app/javascript/ (Vue SPA: dashboard, widget, sdk, portal, superadmin)
- app/views/ (ERB templates for vite-plugin-ruby entrypoint resolution)
- app/helpers/, app/assets/ (Rails view helpers, static assets)
- enterprise/ (Enterprise edition frontend overlay)
- config/vite.json, vite.config.ts, bin/vite (Vite-Rails toolchain)
- package.json, pnpm-lock.yaml, tailwind/postcss/eslint configs
- Gemfile, Gemfile.lock (vite_rails gem for bin/vite binstub)

Excluded Rails backend: controllers, models, services, jobs, mailers,
policies, db, lib, spec, public, node_modules.

Update references to the new frontend location:
- .gitignore: exclude frontend build artifacts (node_modules, tmp, packs),
  keep frontend/bin/ and frontend/vendor/ via negation
- backend/scripts/parity_frontend_smoke.sh: CHATWOOT_DIR default
  reference/chatwoot -> ../frontend
- backend/scripts/parity_frontend_browser_smoke.mjs: same default update
- AGENTS.md: add frontend section with Rails/Vite coupling notes
- README: architecture tree includes frontend/

frontend/app/javascript/dashboard/components-next/label/AddLabel.vue

@@ -0,0 +1,49 @@
+<script setup>
+import { ref } from 'vue';
+import { useI18n } from 'vue-i18n';
+
+import DropdownMenu from 'dashboard/components-next/dropdown-menu/DropdownMenu.vue';
+
+defineProps({
+  labelMenuItems: {
+    type: Array,
+    default: () => [],
+  },
+});
+
+const emit = defineEmits(['updateLabel']);
+
+const { t } = useI18n();
+
+const showDropdown = ref(false);
+</script>
+
+<template>
+  <div class="relative">
+    <button
+      class="flex items-center gap-1 px-2 py-1 rounded-md outline-dashed h-6 outline-1 outline-n-slate-6 hover:bg-n-alpha-2"
+      :class="{ 'bg-n-alpha-2': showDropdown }"
+      @click="showDropdown = !showDropdown"
+    >
+      <span class="i-lucide-plus" />
+      <span class="text-sm text-n-slate-11">
+        {{ t('LABEL.TAG_BUTTON') }}
+      </span>
+    </button>
+    <DropdownMenu
+      v-if="showDropdown"
+      v-on-clickaway="() => (showDropdown = false)"
+      :menu-items="labelMenuItems"
+      show-search
+      class="z-[100] w-48 mt-2 ltr:left-0 rtl:right-0 top-full max-h-52"
+      @action="emit('updateLabel', $event)"
+    >
+      <template #thumbnail="{ item }">
+        <div
+          class="rounded-sm size-2"
+          :style="{ backgroundColor: item.thumbnail.color }"
+        />
+      </template>
+    </DropdownMenu>
+  </div>
+</template>