feat: Implement Phase 2, 3, 4 - Module Settings System with Schema Forms and Addon API

Phase 2: Schema-Based Form System
- Add ModuleSettingsController with GET/POST/schema endpoints
- Create SchemaField component supporting 8 field types (text, textarea, email, url, number, toggle, checkbox, select)
- Create SchemaForm component for automatic form generation from schema
- Add ModuleSettings page with dynamic routing (/settings/modules/:moduleId)
- Add useModuleSettings React hook for settings management
- Implement NewsletterSettings as example with 8 configurable fields
- Add has_settings flag to module registry
- Settings stored as woonoow_module_{module_id}_settings

Phase 3: Advanced Features
- Create windowAPI.ts exposing React, hooks, components, icons, utils to addons via window.WooNooW
- Add DynamicComponentLoader for loading external React components
- Create TypeScript definitions (woonoow-addon.d.ts) for addon developers
- Initialize Window API in App.tsx on mount
- Enable custom React components for addon settings pages

Phase 4: Production Polish & Example
- Create complete Biteship addon example demonstrating both approaches:
  * Schema-based settings (no build required)
  * Custom React component (with build)
- Add comprehensive README with installation and testing guide
- Include package.json with esbuild configuration
- Demonstrate window.WooNooW API usage in custom component

Bug Fixes:
- Fix footer newsletter form visibility (remove redundant module check)
- Fix footer contact_data and social_links not saving (parameter name mismatch: snake_case vs camelCase)
- Fix useModules hook returning undefined (remove .data wrapper, add fallback)
- Add optional chaining to footer settings rendering
- Fix TypeScript errors in woonoow-addon.d.ts (use any for external types)

Files Added (15):
- includes/Api/ModuleSettingsController.php
- includes/Modules/NewsletterSettings.php
- admin-spa/src/components/forms/SchemaField.tsx
- admin-spa/src/components/forms/SchemaForm.tsx
- admin-spa/src/routes/Settings/ModuleSettings.tsx
- admin-spa/src/hooks/useModuleSettings.ts
- admin-spa/src/lib/windowAPI.ts
- admin-spa/src/components/DynamicComponentLoader.tsx
- types/woonoow-addon.d.ts
- examples/biteship-addon/biteship-addon.php
- examples/biteship-addon/src/Settings.jsx
- examples/biteship-addon/package.json
- examples/biteship-addon/README.md
- PHASE_2_3_4_SUMMARY.md

Files Modified (11):
- admin-spa/src/App.tsx
- admin-spa/src/hooks/useModules.ts
- admin-spa/src/routes/Appearance/Footer.tsx
- admin-spa/src/routes/Settings/Modules.tsx
- customer-spa/src/hooks/useModules.ts
- customer-spa/src/layouts/BaseLayout.tsx
- customer-spa/src/components/NewsletterForm.tsx
- includes/Api/Routes.php
- includes/Api/ModulesController.php
- includes/Core/ModuleRegistry.php
- woonoow.php

API Endpoints Added:
- GET /woonoow/v1/modules/{module_id}/settings
- POST /woonoow/v1/modules/{module_id}/settings
- GET /woonoow/v1/modules/{module_id}/schema

For Addon Developers:
- Schema-based: Define settings via woonoow/module_settings_schema filter
- Custom React: Build component using window.WooNooW API, externalize react/react-dom
- Both approaches use same storage and retrieval methods
- TypeScript definitions provided for type safety
- Complete working example (Biteship) included

customer-spa/src/hooks/useModules.ts

@@ -14,7 +14,8 @@ export function useModules() {
     queryKey: ['modules-enabled'],
     queryFn: async () => {
       const response = await api.get('/modules/enabled') as any;
-      return response.data;
+      // api.get returns the data directly, not wrapped in .data
+      return response || { enabled: [] };
     },
     staleTime: 5 * 60 * 1000, // Cache for 5 minutes
   });