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/html-sanitizer/CHANGELOG.md

@@ -0,0 +1,31 @@
+CHANGELOG
+=========
+
+8.0
+---
+
+ * Remove `MastermindsParser`; use `NativeParser` instead
+ * Add argument `$context` to `ParserInterface::parse()`
+
+7.4
+---
+
+ * Use the native HTML5 parser when using PHP 8.4+
+ * Deprecate `MastermindsParser`; use `NativeParser` instead
+ * [BC BREAK] `ParserInterface::parse()` can now return `\Dom\Node|\DOMNode|null` instead of just `\DOMNode|null`
+ * Add argument `$context` to `ParserInterface::parse()`
+
+7.2
+---
+
+ * Add support for configuring the default action to block or allow unconfigured elements instead of dropping them
+
+6.4
+---
+
+ * Add support for sanitizing unlimited length of HTML document
+
+6.1
+---
+
+ * Add the component as experimental