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-php84/README.md

@@ -0,0 +1,23 @@
+Symfony Polyfill / Php84
+========================
+
+This component provides features added to PHP 8.4 core:
+
+- [`array_find`, `array_find_key`, `array_any` and `array_all`](https://wiki.php.net/rfc/array_find)
+- [`bcdivmod`](https://wiki.php.net/rfc/add_bcdivmod_to_bcmath)
+- [`Deprecated`](https://wiki.php.net/rfc/deprecated_attribute)
+- `CURL_HTTP_VERSION_3` and `CURL_HTTP_VERSION_3ONLY` constants
+- [`fpow`](https://wiki.php.net/rfc/raising_zero_to_power_of_negative_number)
+- [`grapheme_str_split`](https://wiki.php.net/rfc/grapheme_str_split)
+- [`mb_trim`, `mb_ltrim` and `mb_rtrim`](https://wiki.php.net/rfc/mb_trim)
+- [`mb_ucfirst` and `mb_lcfirst`](https://wiki.php.net/rfc/mb_ucfirst)
+- [`PDO` driver specific sub-classes](https://wiki.php.net/rfc/pdo_driver_specific_subclasses)
+- [`ReflectionConstant`](https://github.com/php/php-src/pull/13669)
+
+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).