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/message/bubbles/Unsupported.vue

@@ -0,0 +1,27 @@
+<script setup>
+import { computed } from 'vue';
+import { useMessageContext } from '../provider.js';
+import { useInbox } from 'dashboard/composables/useInbox';
+import BaseBubble from './Base.vue';
+
+const { inboxId } = useMessageContext();
+
+const { isAFacebookInbox, isAnInstagramChannel, isATiktokChannel } = useInbox(
+  inboxId.value
+);
+
+const unsupportedMessageKey = computed(() => {
+  if (isAFacebookInbox.value)
+    return 'CONVERSATION.UNSUPPORTED_MESSAGE_FACEBOOK';
+  if (isAnInstagramChannel.value)
+    return 'CONVERSATION.UNSUPPORTED_MESSAGE_INSTAGRAM';
+  if (isATiktokChannel.value) return 'CONVERSATION.UNSUPPORTED_MESSAGE_TIKTOK';
+  return 'CONVERSATION.UNSUPPORTED_MESSAGE';
+});
+</script>
+
+<template>
+  <BaseBubble class="px-4 py-3 text-sm" data-bubble-name="unsupported">
+    {{ $t(unsupportedMessageKey) }}
+  </BaseBubble>
+</template>