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/sebastian/version/ChangeLog.md

@@ -0,0 +1,25 @@
+# ChangeLog
+
+All notable changes are documented in this file using the [Keep a CHANGELOG](https://keepachangelog.com/) principles.
+
+## [3.0.2] - 2020-09-28
+
+### Changed
+
+* Changed PHP version constraint in `composer.json` from `^7.3 || ^8.0` to `>=7.3`
+
+## [3.0.1] - 2020-06-26
+
+### Added
+
+* This component is now supported on PHP 8
+
+## [3.0.0] - 2020-01-21
+
+### Removed
+
+* This component is no longer supported on PHP 7.1 and PHP 7.2
+
+[3.0.2]: https://github.com/sebastianbergmann/version/compare/3.0.1...3.0.2
+[3.0.1]: https://github.com/sebastianbergmann/version/compare/3.0.0...3.0.1
+[3.0.0]: https://github.com/sebastianbergmann/version/compare/2.0.1...3.0.0