Add link-target and auto-redirect options to booking/login blocks

The booking block gains a loginPageId attribute choosing which page its
logged-out "log in to book a lesson" link points to (default remains the
WordPress login screen), and the student-login block gains a
bookingPageId attribute controlling the logged-in "View available
lessons" link and the post-login redirect target (default remains the
current page). Both blocks also gain an autoRedirect toggle, off by
default, that sends the visitor straight to the target page; block
rendering starts after output, so the redirect runs on
template_redirect by parsing the queried page's content for the block,
with a self-target guard against redirect loops. The link targets are
also available to the shortcodes as login_page_id/booking_page_id.

Also fixes a pre-existing fatal: WordPress passes an empty string (not
an array) to shortcode callbacks when a shortcode is used without
attributes, so bare [us_booking] etc. threw a TypeError against the
strictly-typed render(array $atts) methods. ShortcodeRegistrar now
wraps each callback to normalize non-array attribute values.

Closes #51

Co-Authored-By: Claude Fable 5 <[email protected]>

src/Booking/BookingPage.php

@@ -4,22 +4,24 @@ declare(strict_types=1);
 namespace Unsupervised\Schedular\Booking;
 
 use Unsupervised\Schedular\Auth\RoleManager;
+use Unsupervised\Schedular\Val;
 
 class BookingPage {
 
 	/**
-	 * Renders the booking shortcode output.
+	 * Renders the booking shortcode/block output.
 	 *
-	 * @param array<string> $atts Shortcode attributes (unused — reserved for future options).
+	 * @param array<int|string, mixed> $atts Block attributes (`loginPageId`) or
+	 *                                       shortcode attributes (`login_page_id`).
 	 */
-	public function render( array $atts ): string { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter.Found
+	public function render( array $atts ): string {
 		if ( ! is_user_logged_in() ) {
-			$permalink = get_permalink();
+			$loginPageId = Val::int( $atts['loginPageId'] ?? $atts['login_page_id'] ?? 0 );
 
 			return sprintf(
 				'<p>%s <a href="%s">%s</a>.</p>',
 				esc_html__( 'Please', 'unsupervised-schedular' ),
-				esc_url( wp_login_url( false === $permalink ? '' : $permalink ) ),
+				esc_url( $this->loginUrl( $loginPageId ) ),
 				esc_html__( 'log in to book a lesson', 'unsupervised-schedular' )
 			);
 		}
@@ -35,4 +37,23 @@ class BookingPage {
 		include USC_PLUGIN_DIR . 'templates/frontend/booking-page.php';
 		return (string) ob_get_clean();
 	}
+
+	/**
+	 * URL the logged-out prompt sends visitors to: the chosen login page when
+	 * one is configured (and still exists), otherwise the WordPress login
+	 * screen with a redirect back to the current page.
+	 */
+	public function loginUrl( int $loginPageId ): string {
+		if ( $loginPageId > 0 ) {
+			$url = get_permalink( $loginPageId );
+
+			if ( is_string( $url ) ) {
+				return $url;
+			}
+		}
+
+		$permalink = get_permalink();
+
+		return wp_login_url( false === $permalink ? '' : $permalink );
+	}
 }