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>

assets/css/frontend.css

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+.us-login-form label {
+    display: block;
+    margin-bottom: 4px;
+    font-weight: 600;
+}
+
+.us-login-form input[type="text"],
+.us-login-form input[type="password"] {
+    width: 100%;
+    max-width: 340px;
+    padding: 8px;
+    border: 1px solid #ccc;
+    border-radius: 4px;
+}
+
+.us-error {
+    color: #c00;
+    border-left: 4px solid #c00;
+    padding-left: 8px;
+}
+
+#us-booking-app .us-slot {
+    border: 1px solid #ddd;
+    border-radius: 4px;
+    padding: 12px 16px;
+    margin-bottom: 8px;
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+}
+
+#us-booking-error {
+    color: #c00;
+    margin-top: 8px;
+}

assets/js/booking.js

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+/* global usScheduler */
+(function () {
+    'use strict';
+
+    const app = document.getElementById('us-booking-app');
+    if (!app) return;
+
+    const slotList    = document.getElementById('us-slot-list');
+    const confirm     = document.getElementById('us-booking-confirmation');
+    const errorBox    = document.getElementById('us-booking-error');
+    const { restUrl, nonce } = usScheduler;
+
+    function apiFetch(path, options = {}) {
+        return fetch(restUrl + path, {
+            ...options,
+            headers: {
+                'Content-Type': 'application/json',
+                'X-WP-Nonce': nonce,
+                ...(options.headers || {}),
+            },
+        }).then(async (res) => {
+            const data = await res.json();
+            if (!res.ok) throw new Error(data.message || 'Request failed');
+            return data;
+        });
+    }
+
+    function showError(message) {
+        errorBox.textContent = message;
+        errorBox.style.display = 'block';
+    }
+
+    function renderSlots(slots) {
+        if (!slots.length) {
+            slotList.innerHTML = '<p>No available lesson slots at this time.</p>';
+            return;
+        }
+
+        slotList.innerHTML = slots.map((slot) => `
+            <div class="us-slot">
+                <span>${escHtml(slot.start_dt)} – ${escHtml(slot.end_dt)}</span>
+                <button data-slot-id="${slot.id}" class="us-book-btn">Book</button>
+            </div>
+        `).join('');
+
+        slotList.querySelectorAll('.us-book-btn').forEach((btn) => {
+            btn.addEventListener('click', () => bookSlot(Number(btn.dataset.slotId)));
+        });
+    }
+
+    function escHtml(str) {
+        return String(str)
+            .replace(/&/g, '&amp;')
+            .replace(/</g, '&lt;')
+            .replace(/>/g, '&gt;')
+            .replace(/"/g, '&quot;');
+    }
+
+    function bookSlot(slotId) {
+        errorBox.style.display = 'none';
+
+        apiFetch('bookings', {
+            method: 'POST',
+            body: JSON.stringify({ slot_id: slotId }),
+        })
+            .then(() => {
+                slotList.style.display = 'none';
+                confirm.style.display  = 'block';
+            })
+            .catch((err) => showError(err.message));
+    }
+
+    apiFetch('availability')
+        .then(renderSlots)
+        .catch((err) => showError(err.message));
+}());