feat: implement onboarding wizard and fix help page navigation

Core Features:
- Add Quick Setup Wizard for new users with multi-step flow
- Implement distraction-free onboarding layout (no sidebar/header)
- Create OnboardingController API endpoint for saving settings
- Redirect new users to /setup automatically on first admin access

Onboarding Components:
- StepMode: Select between full/minimal store modes
- StepHomepage: Choose or auto-create homepage
- StepAppearance: Configure container width and primary color
- StepProgress: Visual progress indicator

Navigation & Routing:
- Fix Help page links to use react-router navigation (prevent full reload)
- Update onboarding completion redirect to /appearance/pages
- Add manual onboarding access via Settings > Store Details

UI/UX Improvements:
- Enable dark mode support for Page Editor
- Fix page title rendering in onboarding dropdown
- Improve title fallback logic (title.rendered, title, post_title)

Type Safety:
- Unify PageItem interface across all components
- Add 'default' to containerWidth type definition
- Add missing properties (permalink_base, has_template, icon)

Files Modified:
- includes/Api/OnboardingController.php
- includes/Api/Routes.php
- includes/Admin/Assets.php
- admin-spa/src/App.tsx
- admin-spa/src/routes/Onboarding/*
- admin-spa/src/routes/Help/DocContent.tsx
- admin-spa/src/routes/Settings/Store.tsx
- admin-spa/src/routes/Appearance/Pages/*

includes/Admin/Assets.php

@@ -1,4 +1,5 @@
 <?php
+
 namespace WooNooW\Admin;
 
 use WooNooW\Compat\MenuProvider;
@@ -74,6 +75,7 @@ class Assets
             'pluginUrl' => trailingslashit(plugins_url('/', dirname(__DIR__))),
             'storeUrl' => self::get_spa_url(),
             'customerSpaEnabled' => get_option('woonoow_customer_spa_enabled', false),
+            'onboardingCompleted' => get_option('woonoow_onboarding_completed', false),
         ]);
         wp_add_inline_script($handle, 'window.WNW_CONFIG = window.WNW_CONFIG || WNW_CONFIG;', 'after');
 
@@ -119,15 +121,15 @@ class Assets
         // 2) Print a real module tag in the footer to load Vite client + app
         add_action('admin_print_footer_scripts', function () use ($dev_url) {
             // 1) React Refresh preamble (required by @vitejs/plugin-react)
-            ?>
+?>
             <script type="module">
                 import RefreshRuntime from "<?php echo esc_url($dev_url); ?>/@react-refresh";
                 RefreshRuntime.injectIntoGlobalHook(window);
-                window.$RefreshReg$ = () => { };
+                window.$RefreshReg$ = () => {};
                 window.$RefreshSig$ = () => (type) => type;
                 window.__vite_plugin_react_preamble_installed__ = true;
             </script>
-            <?php
+<?php
 
             // 2) Vite client (HMR)
             printf('<script type="module" src="%s/@vite/client"></script>' . "\n", esc_url($dev_url));
@@ -199,6 +201,7 @@ class Assets
             'pluginUrl' => trailingslashit(plugins_url('/', dirname(__DIR__))),
             'storeUrl' => self::get_spa_url(),
             'customerSpaEnabled' => get_option('woonoow_customer_spa_enabled', false),
+            'onboardingCompleted' => get_option('woonoow_onboarding_completed', false),
         ]);
 
         // WordPress REST API settings (for media upload compatibility)
@@ -318,15 +321,15 @@ class Assets
     {
         $appearance_settings = get_option('woonoow_appearance_settings', []);
         $spa_page_id = $appearance_settings['general']['spa_page'] ?? 0;
-        
+
         if ($spa_page_id) {
             $spa_url = get_permalink($spa_page_id);
             if ($spa_url) {
                 return trailingslashit($spa_url);
             }
         }
-        
+
         // Fallback to /store/ if no SPA page configured
         return home_url('/store/');
     }
-}
+}