feat(classes): add class days and meeting times to class forms

Let admins set the weekly schedule on the class and show it in lists, details, and session generation.

src/utils/classSchedule.test.js

@@ -0,0 +1,22 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import { formatClassDays, formatClassTime, formatClassSchedule } from './classSchedule.js';
+
+describe('class schedule display', () => {
+  it('formats weekdays in Iran week order', () => {
+    assert.equal(formatClassDays([1, 6]), 'شنبه و دوشنبه');
+  });
+
+  it('formats start and end times', () => {
+    assert.equal(formatClassTime('19:00', '21:00'), '19:00 – 21:00');
+    assert.equal(formatClassTime('19:00', ''), '19:00');
+  });
+
+  it('joins days and time for a class schedule label', () => {
+    assert.equal(
+      formatClassSchedule({ days: [6, 1], startTime: '19:00', endTime: '21:00' }),
+      'شنبه و دوشنبه | 19:00 – 21:00'
+    );
+    assert.equal(formatClassSchedule({}), '');
+  });
+});