refactor: Cleanup git state - commit all staged changes

Major refactoring cleanup:
- Add new controller architecture (class-controller-*.php)
- Add new settings-v2 UI (views/settings-v2/)
- Add new CSS architecture (agentic-sidebar.css, tokens)
- Add esbuild build pipeline (scripts/build.js, package.json)
- Add composer dependencies (vendor/)
- Add frontend src directory (assets/js/src/index.jsx)
- Add documentation files
- Remove old/obsolete files (class-settings.php, old CSS)

This commits all pending changes from previous refactoring efforts.

vendor/symfony/polyfill-intl-idn/README.md

@@ -0,0 +1,12 @@
+Symfony Polyfill / Intl: Idn
+============================
+
+This component provides [`idn_to_ascii`](https://php.net/idn-to-ascii) and [`idn_to_utf8`](https://php.net/idn-to-utf8) functions to users who run php versions without the [Intl](https://php.net/intl) extension.
+
+More information can be found in the
+[main Polyfill README](https://github.com/symfony/polyfill/blob/main/README.md).
+
+License
+=======
+
+This library is released under the [MIT license](LICENSE).