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/shared/helpers/emoji.js

@@ -0,0 +1,47 @@
+/**
+ * Detects support for emoji character sets.
+ *
+ * Based on the Modernizr emoji detection.
+ * https://github.com/Modernizr/Modernizr/blob/347ddb078116cee91b25b6e897e211b023f9dcb4/feature-detects/emoji.js
+ *
+ * @return {Boolean} true or false
+ * @example
+ *
+ * hasEmojiSupport()
+ * // => true|false
+ */
+export const hasEmojiSupport = () => {
+  const pixelRatio = window.devicePixelRatio || 1;
+  const offset = 12 * pixelRatio;
+  const node = document.createElement('canvas');
+
+  // canvastext support
+  if (
+    !node.getContext ||
+    !node.getContext('2d') ||
+    typeof node.getContext('2d').fillText !== 'function'
+  ) {
+    return false;
+  }
+
+  const ctx = node.getContext('2d');
+
+  ctx.fillStyle = '#f00';
+  ctx.textBaseline = 'top';
+  ctx.font = '32px Arial';
+  ctx.fillText('\ud83d\udc28', 0, 0); // U+1F428 KOALA
+  return ctx.getImageData(offset, offset, 1, 1).data[0] !== 0;
+};
+
+export const removeEmoji = text => {
+  if (text) {
+    return text
+      .replace(
+        /([\u2700-\u27BF]|[\uE000-\uF8FF]|\uD83C[\uDC00-\uDFFF]|\uD83D[\uDC00-\uDFFF]|[\u2011-\u26FF]|\uD83E[\uDD10-\uDDFF])/g,
+        ''
+      )
+      .replace(/\s+/g, ' ')
+      .trim();
+  }
+  return '';
+};