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-php80/README.md

@@ -0,0 +1,25 @@
+Symfony Polyfill / Php80
+========================
+
+This component provides features added to PHP 8.0 core:
+
+- [`Stringable`](https://php.net/stringable) interface
+- [`fdiv`](https://php.net/fdiv)
+- [`ValueError`](https://php.net/valueerror) class
+- [`UnhandledMatchError`](https://php.net/unhandledmatcherror) class
+- `FILTER_VALIDATE_BOOL` constant
+- [`get_debug_type`](https://php.net/get_debug_type)
+- [`PhpToken`](https://php.net/phptoken) class
+- [`preg_last_error_msg`](https://php.net/preg_last_error_msg)
+- [`str_contains`](https://php.net/str_contains)
+- [`str_starts_with`](https://php.net/str_starts_with)
+- [`str_ends_with`](https://php.net/str_ends_with)
+- [`get_resource_id`](https://php.net/get_resource_id)
+
+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).