Initial plugin scaffold: lesson scheduling WordPress plugin

- Custom DB tables for availability slots and lesson bookings
- Instructor (wp-admin) and student (front-end) roles with custom capabilities
- REST API under us-scheduler/v1 for availability CRUD and booking
- [us_booking] and [us_student_login] shortcodes for student front end
- PHPUnit + Brain\Monkey unit test suite (29 tests)
- Gitea Actions CI: lint, PHPStan, tests on PHP 8.1/8.2/8.3, no-debug check
- Feature docs under docs/features/

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/frontend/booking-page.php

@@ -0,0 +1,16 @@
+<?php
+declare(strict_types=1);
+
+if (! defined('ABSPATH')) {
+    exit;
+}
+?>
+<div id="us-booking-app" data-nonce="<?php echo esc_attr(wp_create_nonce('wp_rest')); ?>">
+    <div id="us-slot-list">
+        <p><?php esc_html_e('Loading available slots…', 'unsupervised-schedular'); ?></p>
+    </div>
+    <div id="us-booking-confirmation" style="display:none;">
+        <p><?php esc_html_e('Your lesson has been booked. The instructor will confirm shortly.', 'unsupervised-schedular'); ?></p>
+    </div>
+    <div id="us-booking-error" style="display:none;" role="alert"></div>
+</div>