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/Auth/LoginPage.php

@@ -8,23 +8,25 @@ use Unsupervised\Schedular\Val;
 class LoginPage {
 
 	/**
-	 * Renders the student login shortcode output.
+	 * Renders the student login shortcode/block output.
 	 *
-	 * @param array<string> $atts Shortcode attributes (unused — reserved for future options).
+	 * @param array<int|string, mixed> $atts Block attributes (`bookingPageId`) or
+	 *                                       shortcode attributes (`booking_page_id`).
 	 */
-	public function render( array $atts ): string { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter.Found
+	public function render( array $atts ): string {
+		$bookingPageId = Val::int( $atts['bookingPageId'] ?? $atts['booking_page_id'] ?? 0 );
+
 		if ( is_user_logged_in() ) {
-			$redirect = esc_url( (string) get_permalink() );
 			return sprintf(
 				'<p>%s <a href="%s">%s</a>.</p>',
 				esc_html__( 'You are already logged in.', 'unsupervised-schedular' ),
-				$redirect,
+				esc_url( $this->bookingUrl( $bookingPageId ) ?? (string) get_permalink() ),
 				esc_html__( 'View available lessons', 'unsupervised-schedular' )
 			);
 		}
 
 		$error    = '';
-		$redirect = sanitize_url( (string) get_permalink() );
+		$redirect = sanitize_url( $this->bookingUrl( $bookingPageId ) ?? (string) get_permalink() );
 
 		if ( isset( $_POST['us_login'] ) && check_admin_referer( 'us_student_login' ) ) {
 			$credentials = [
@@ -48,4 +50,19 @@ class LoginPage {
 		include USC_PLUGIN_DIR . 'templates/frontend/login-page.php';
 		return (string) ob_get_clean();
 	}
+
+	/**
+	 * Permalink of the configured booking page, or null when no page is
+	 * chosen (or the chosen page no longer exists). Logged-in visitors are
+	 * linked (and redirected after login) there instead of the current page.
+	 */
+	public function bookingUrl( int $bookingPageId ): ?string {
+		if ( $bookingPageId <= 0 ) {
+			return null;
+		}
+
+		$url = get_permalink( $bookingPageId );
+
+		return is_string( $url ) ? $url : null;
+	}
 }