fix: auto-login after checkout, ThankYou guest buttons, forgot password page

1. Auto-login after checkout:
   - Added wp_set_auth_cookie() and wp_set_current_user() in CheckoutController
   - Auto-registered users are now logged in when thank-you page loads

2. ThankYou page guest buttons:
   - Added 'Login / Create Account' button for guests
   - Shows for both receipt and basic templates
   - No more dead-end after placing order as guest

3. Forgot password flow:
   - Created ForgotPassword page component (/forgot-password route)
   - Added forgot_password API endpoint in AuthController
   - Uses WordPress retrieve_password() for reset email
   - Replaced wp-login.php link in Login page

customer-spa/src/App.tsx

@@ -16,6 +16,7 @@ import ThankYou from './pages/ThankYou';
 import Account from './pages/Account';
 import Wishlist from './pages/Wishlist';
 import Login from './pages/Login';
+import ForgotPassword from './pages/ForgotPassword';
 
 // Create QueryClient instance
 const queryClient = new QueryClient({
@@ -85,8 +86,9 @@ function AppRoutes() {
         {/* Wishlist - Public route accessible to guests */}
         <Route path="/wishlist" element={<Wishlist />} />
 
-        {/* Login */}
+        {/* Login & Auth */}
         <Route path="/login" element={<Login />} />
+        <Route path="/forgot-password" element={<ForgotPassword />} />
 
         {/* My Account */}
         <Route path="/my-account/*" element={<Account />} />