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/cache.js

@@ -0,0 +1,43 @@
+import { LocalStorage } from './localStorage';
+
+// Default cache expiry is 24 hours
+const DEFAULT_EXPIRY = 24 * 60 * 60 * 1000;
+
+export const getFromCache = (key, expiry = DEFAULT_EXPIRY) => {
+  try {
+    const cached = LocalStorage.get(key);
+    if (!cached) return null;
+
+    const { data, timestamp } = cached;
+    const isExpired = Date.now() - timestamp > expiry;
+
+    if (isExpired) {
+      LocalStorage.remove(key);
+      return null;
+    }
+
+    return data;
+  } catch (error) {
+    return null;
+  }
+};
+
+export const setCache = (key, data) => {
+  try {
+    const cacheData = {
+      data,
+      timestamp: Date.now(),
+    };
+    LocalStorage.set(key, cacheData);
+  } catch (error) {
+    // Ignore cache errors
+  }
+};
+
+export const clearCache = key => {
+  try {
+    LocalStorage.remove(key);
+  } catch (error) {
+    // Ignore cache errors
+  }
+};