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/nikic/php-parser/lib/PhpParser/Node/Scalar/InterpolatedString.php

@@ -0,0 +1,34 @@
+<?php declare(strict_types=1);
+
+namespace PhpParser\Node\Scalar;
+
+use PhpParser\Node\Expr;
+use PhpParser\Node\InterpolatedStringPart;
+use PhpParser\Node\Scalar;
+
+class InterpolatedString extends Scalar {
+    /** @var (Expr|InterpolatedStringPart)[] list of string parts */
+    public array $parts;
+
+    /**
+     * Constructs an interpolated string node.
+     *
+     * @param (Expr|InterpolatedStringPart)[] $parts Interpolated string parts
+     * @param array<string, mixed> $attributes Additional attributes
+     */
+    public function __construct(array $parts, array $attributes = []) {
+        $this->attributes = $attributes;
+        $this->parts = $parts;
+    }
+
+    public function getSubNodeNames(): array {
+        return ['parts'];
+    }
+
+    public function getType(): string {
+        return 'Scalar_InterpolatedString';
+    }
+}
+
+// @deprecated compatibility alias
+class_alias(InterpolatedString::class, Encapsed::class);