feat(classes): store weekdays and meeting times on the class

Keep the class schedule on the class itself so SMS and listings do not have to infer days and hours from sessions.

utils/classSchedule.test.js

@@ -6,6 +6,9 @@ const {
   formatCourseTime,
   formatClassDays,
   formatClassStartDate,
+  formatClassDaysFromIndexes,
+  normalizeWeekdays,
+  normalizeClockTime,
   buildClassScheduleContext
 } = require('./classSchedule');
 
@@ -56,4 +59,40 @@ describe('class schedule SMS helpers', () => {
 
     assert.equal(context.courseTime, 'از 10 تا 12');
   });
+
+  it('prefers stored class days and times over inferred sessions', () => {
+    const atNoon = (year, month, day) => new Date(year, month - 1, day, 12, 0, 0);
+    const context = buildClassScheduleContext(
+      {
+        startDate: atNoon(2026, 8, 15),
+        days: [6, 1],
+        startTime: '18:00',
+        endTime: '20:00'
+      },
+      [
+        { day: atNoon(2026, 8, 16), startTime: '19:00', endTime: '21:00' }
+      ]
+    );
+
+    assert.equal(context.classDays, 'شنبه و دوشنبه');
+    assert.equal(context.courseTime, 'از 18 تا 20');
+  });
+});
+
+describe('class weekday and time normalization', () => {
+  it('deduplicates weekdays and sorts them in Iran week order', () => {
+    assert.deepEqual(normalizeWeekdays([1, 6, 1, 3, 9, '2']), [6, 1, 2, 3]);
+  });
+
+  it('normalizes clock times to HH:mm', () => {
+    assert.equal(normalizeClockTime('19'), '19:00');
+    assert.equal(normalizeClockTime('9:5'), '09:05');
+    assert.equal(normalizeClockTime('19:00'), '19:00');
+    assert.equal(normalizeClockTime('25:00'), '');
+    assert.equal(normalizeClockTime(''), '');
+  });
+
+  it('formats stored weekday indexes as Persian day names', () => {
+    assert.equal(formatClassDaysFromIndexes([1, 6]), 'شنبه و دوشنبه');
+  });
 });