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/psr/http-factory/src/UriFactoryInterface.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace Psr\Http\Message;
+
+interface UriFactoryInterface
+{
+    /**
+     * Create a new URI.
+     *
+     * @param string $uri
+     *
+     * @return UriInterface
+     *
+     * @throws \InvalidArgumentException If the given URI cannot be parsed.
+     */
+    public function createUri(string $uri = ''): UriInterface;
+}