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/api/contacts.js

@@ -0,0 +1,28 @@
+import { API } from 'widget/helpers/axios';
+
+const buildUrl = endPoint => `/api/v1/${endPoint}${window.location.search}`;
+
+export default {
+  get() {
+    return API.get(buildUrl('widget/contact'));
+  },
+  update(userObject) {
+    return API.patch(buildUrl('widget/contact'), userObject);
+  },
+  setUser(identifier, userObject) {
+    return API.patch(buildUrl('widget/contact/set_user'), {
+      identifier,
+      ...userObject,
+    });
+  },
+  setCustomAttributes(customAttributes = {}) {
+    return API.patch(buildUrl('widget/contact'), {
+      custom_attributes: customAttributes,
+    });
+  },
+  deleteCustomAttribute(customAttribute) {
+    return API.post(buildUrl('widget/contact/destroy_custom_attributes'), {
+      custom_attributes: [customAttribute],
+    });
+  },
+};