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/widgets/SettingIntroBanner.vue

@@ -0,0 +1,28 @@
+<script>
+export default {
+  props: {
+    headerTitle: {
+      type: String,
+      default: '',
+    },
+    headerContent: {
+      type: String,
+      default: '',
+    },
+  },
+};
+</script>
+
+<template>
+  <div class="border-b border-solid border-n-weak/60">
+    <div class="max-w-7xl w-full mx-auto pt-4 pb-0 px-6">
+      <h2 class="text-2xl text-n-slate-12 mb-1 font-medium">
+        {{ headerTitle }}
+      </h2>
+      <p v-if="headerContent" class="w-full text-n-slate-11 text-sm mb-2">
+        {{ headerContent }}
+      </p>
+      <slot />
+    </div>
+  </div>
+</template>