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.

includes/class-controller-models.php

@@ -0,0 +1,78 @@
+<?php
+/**
+ * Models REST Controller
+ *
+ * Handles model listing and refresh operations.
+ *
+ * @package WP_Agentic_Writer
+ */
+
+/**
+ * Class WP_Agentic_Writer_Controller_Models
+ *
+ * REST controller for model operations.
+ *
+ * @since 0.3.0
+ */
+class WP_Agentic_Writer_Controller_Models {
+
+    /**
+     * Sidebar instance for dependency access.
+     *
+     * @var WP_Agentic_Writer_Gutenberg_Sidebar
+     */
+    private $sidebar;
+
+    /**
+     * Constructor.
+     *
+     * @since 0.3.0
+     * @param WP_Agentic_Writer_Gutenberg_Sidebar $sidebar Sidebar instance.
+     */
+    public function __construct( $sidebar ) {
+        $this->sidebar = $sidebar;
+    }
+
+    /**
+     * Handle get models request.
+     *
+     * @since 0.1.0
+     * @return WP_REST_Response|WP_Error Response.
+     */
+    public function handle_get_models() {
+        $provider = WP_Agentic_Writer_OpenRouter_Provider::get_instance();
+        $models   = $provider->get_cached_models();
+
+        if ( is_wp_error( $models ) ) {
+            return $models;
+        }
+
+        return new WP_REST_Response( $models, 200 );
+    }
+
+    /**
+     * Handle refresh models request.
+     *
+     * @since 0.1.0
+     * @return WP_REST_Response|WP_Error Response.
+     */
+    public function handle_refresh_models() {
+        $provider = WP_Agentic_Writer_OpenRouter_Provider::get_instance();
+        $models   = $provider->fetch_and_cache_models( true );
+
+        if ( is_wp_error( $models ) ) {
+            return $models;
+        }
+
+        return new WP_REST_Response(
+            [
+                'models'  => $models,
+                'message' => __(
+                    'Models refreshed successfully.',
+                    'wp-agentic-writer',
+                ),
+            ],
+            200,
+        );
+    }
+}