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/widget/components/AgentTypingBubble.vue

@@ -0,0 +1,30 @@
+<script>
+export default {
+  name: 'AgentTypingBubble',
+};
+</script>
+
+<template>
+  <div class="agent-message-wrap sticky bottom-1">
+    <div class="agent-message">
+      <div class="avatar-wrap" />
+      <div class="message-wrap mt-2">
+        <div
+          class="chat-bubble agent typing-bubble bg-n-background dark:bg-n-solid-3"
+        >
+          <img
+            src="assets/images/typing.gif"
+            alt="Agent is typing a message"
+            class="!w-full"
+          />
+        </div>
+      </div>
+    </div>
+  </div>
+</template>
+
+<style lang="scss" scoped>
+.typing-bubble {
+  @apply max-w-[2.4rem] p-2 ltr:rounded-bl-[1.25rem] rtl:rounded-br-[1.25rem] ltr:rounded-tl-lg rtl:rounded-tr-lg;
+}
+</style>