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/File.vue

@@ -0,0 +1,45 @@
+<script setup>
+import { computed } from 'vue';
+import { useI18n } from 'vue-i18n';
+
+import { useMessageContext } from '../provider.js';
+import BaseAttachmentBubble from './BaseAttachment.vue';
+import FileIcon from 'next/icon/FileIcon.vue';
+
+const { attachments } = useMessageContext();
+
+const { t } = useI18n();
+
+const url = computed(() => {
+  return attachments.value[0].dataUrl;
+});
+
+const fileName = computed(() => {
+  if (url.value) {
+    const filename = url.value.substring(url.value.lastIndexOf('/') + 1);
+    return filename || t('CONVERSATION.UNKNOWN_FILE_TYPE');
+  }
+  return t('CONVERSATION.UNKNOWN_FILE_TYPE');
+});
+
+const fileType = computed(() => {
+  return fileName.value.split('.').pop();
+});
+</script>
+
+<template>
+  <BaseAttachmentBubble
+    icon="i-teenyicons-user-circle-solid"
+    icon-bg-color="bg-n-alpha-3 dark:bg-n-alpha-white"
+    sender-translation-key="CONVERSATION.SHARED_ATTACHMENT.FILE"
+    :content="decodeURI(fileName)"
+    :action="{
+      href: url,
+      label: $t('CONVERSATION.DOWNLOAD'),
+    }"
+  >
+    <template #icon>
+      <FileIcon :file-type="fileType" class="size-4" />
+    </template>
+  </BaseAttachmentBubble>
+</template>