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>

src/Installer.php

@@ -0,0 +1,30 @@
+<?php
+declare(strict_types=1);
+
+namespace Unsupervised\Schedular;
+
+use Unsupervised\Schedular\Data\Schema;
+use Unsupervised\Schedular\Roles\RoleManager;
+
+class Installer
+{
+    public function run(): void
+    {
+        $this->createTables();
+        (new RoleManager())->createRoles();
+        flush_rewrite_rules();
+        update_option('us_schedular_version', USC_VERSION);
+    }
+
+    private function createTables(): void
+    {
+        global $wpdb;
+        $charset = $wpdb->get_charset_collate();
+
+        require_once ABSPATH . 'wp-admin/includes/upgrade.php';
+
+        foreach (Schema::tables($wpdb->prefix, $charset) as $sql) {
+            dbDelta($sql);
+        }
+    }
+}