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

types/woonoow-addon.d.ts

@@ -0,0 +1,161 @@
+/**
+ * WooNooW Addon TypeScript Definitions
+ * 
+ * Type definitions for addon developers using the WooNooW API
+ * 
+ * @package WooNooW
+ * @version 1.0.0
+ */
+
+import type { ComponentType } from 'react';
+
+declare global {
+  interface Window {
+    /**
+     * WooNooW API exposed to addon developers
+     */
+    WooNooW: {
+      React: typeof import('react');
+      ReactDOM: typeof import('react-dom/client');
+      
+      hooks: {
+        useQuery: any;
+        useMutation: any;
+        useQueryClient: any;
+        useModules: () => {
+          isEnabled: (moduleId: string) => boolean;
+          modules: string[];
+        };
+        useModuleSettings: (moduleId: string) => {
+          settings: Record<string, any>;
+          isLoading: boolean;
+          updateSettings: {
+            mutate: (settings: Record<string, any>) => void;
+            isPending: boolean;
+          };
+          saveSetting: (key: string, value: any) => void;
+        };
+      };
+      
+      components: {
+        Button: ComponentType<any>;
+        Input: ComponentType<any>;
+        Label: ComponentType<any>;
+        Textarea: ComponentType<any>;
+        Switch: ComponentType<any>;
+        Select: ComponentType<any>;
+        SelectContent: ComponentType<any>;
+        SelectItem: ComponentType<any>;
+        SelectTrigger: ComponentType<any>;
+        SelectValue: ComponentType<any>;
+        Checkbox: ComponentType<any>;
+        Badge: ComponentType<any>;
+        Card: ComponentType<any>;
+        CardContent: ComponentType<any>;
+        CardDescription: ComponentType<any>;
+        CardFooter: ComponentType<any>;
+        CardHeader: ComponentType<any>;
+        CardTitle: ComponentType<any>;
+        SettingsLayout: ComponentType<{
+          title: string;
+          description?: string;
+          isLoading?: boolean;
+          children: React.ReactNode;
+        }>;
+        SettingsCard: ComponentType<{
+          title: string;
+          description?: string;
+          children: React.ReactNode;
+        }>;
+        SettingsSection: ComponentType<any>;
+        SchemaForm: ComponentType<{
+          schema: FormSchema;
+          initialValues?: Record<string, any>;
+          onSubmit: (values: Record<string, any>) => void | Promise<void>;
+          isSubmitting?: boolean;
+          submitLabel?: string;
+          errors?: Record<string, string>;
+        }>;
+        SchemaField: ComponentType<any>;
+      };
+      
+      icons: {
+        Settings: ComponentType<any>;
+        Save: ComponentType<any>;
+        Trash2: ComponentType<any>;
+        Edit: ComponentType<any>;
+        Plus: ComponentType<any>;
+        X: ComponentType<any>;
+        Check: ComponentType<any>;
+        AlertCircle: ComponentType<any>;
+        Info: ComponentType<any>;
+        Loader2: ComponentType<any>;
+        ChevronDown: ComponentType<any>;
+        ChevronUp: ComponentType<any>;
+        ChevronLeft: ComponentType<any>;
+        ChevronRight: ComponentType<any>;
+      };
+      
+      utils: {
+        api: {
+          get: (endpoint: string) => Promise<any>;
+          post: (endpoint: string, data?: any) => Promise<any>;
+          put: (endpoint: string, data?: any) => Promise<any>;
+          delete: (endpoint: string) => Promise<any>;
+        };
+        toast: {
+          success: (message: string) => void;
+          error: (message: string) => void;
+          info: (message: string) => void;
+          warning: (message: string) => void;
+        };
+        __: (text: string, domain?: string) => string;
+      };
+    };
+  }
+}
+
+/**
+ * Form Schema Types
+ */
+export type FieldType = 'text' | 'textarea' | 'email' | 'url' | 'number' | 'toggle' | 'checkbox' | 'select';
+
+export interface FieldSchema {
+  type: FieldType;
+  label: string;
+  description?: string;
+  placeholder?: string;
+  required?: boolean;
+  default?: any;
+  options?: Record<string, string>;
+  min?: number;
+  max?: number;
+}
+
+export type FormSchema = Record<string, FieldSchema>;
+
+/**
+ * Module Registration
+ */
+export interface ModuleRegistration {
+  id: string;
+  name: string;
+  description: string;
+  version: string;
+  author: string;
+  category: 'marketing' | 'customers' | 'products' | 'shipping' | 'payments' | 'analytics' | 'other';
+  icon: string;
+  features: string[];
+  has_settings?: boolean;
+  settings_component?: string;
+  spa_bundle?: string;
+}
+
+/**
+ * Settings Schema Registration
+ */
+export interface SettingsSchemaRegistration {
+  [moduleId: string]: FormSchema;
+}
+
+export {};