feat: show this month's birthdays and send a greeting SMS

Each owner sees their customers born this Jalali month and can text a custom greeting.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/api/test/birthdays.test.ts

@@ -0,0 +1,52 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import { toGregorian } from '../src/common/jalali';
+import {
+  BIRTHDAY_SMS_DEFAULT,
+  fillBirthdaySmsText,
+  selectMonthBirthdays,
+} from '../src/contacts/birthday-month';
+
+function birth(jy: number, jm: number, jd: number) {
+  const g = toGregorian(jy, jm, jd);
+  return new Date(Date.UTC(g.gy, g.gm - 1, g.gd, 12, 0, 0));
+}
+
+const now = new Date('2026-10-08T08:00:00Z');
+
+describe('تولدهای ماه شمسی', () => {
+  it('فقط متولدین همین ماه را می‌آورد و روزهای مانده را جلوتر می‌گذارد', () => {
+    const result = selectMonthBirthdays(
+      [
+        { id: 'soon', firstName: 'آیدا', lastName: 'کریمی', mobile: '09120000000', birthDate: birth(1370, 7, 20) },
+        { id: 'past', firstName: 'رضا', lastName: 'بهرامی', mobile: null, birthDate: birth(1360, 7, 2) },
+        { id: 'other', firstName: 'پریسا', lastName: 'قاسمی', mobile: '09121111111', birthDate: birth(1369, 6, 30) },
+        { id: 'today', firstName: 'سارا', lastName: 'محمدی', mobile: '09123333333', birthDate: birth(1375, 7, 16) },
+      ],
+      now,
+      2,
+    );
+
+    assert.equal(result.month, 7);
+    assert.equal(result.monthName, 'مهر');
+    assert.equal(result.today, 16);
+    assert.equal(result.total, 3);
+    assert.deepEqual(
+      result.preview.map((row) => row.id),
+      ['today', 'soon'],
+    );
+    assert.deepEqual(
+      result.items.map((row) => row.id),
+      ['today', 'soon', 'past'],
+    );
+    assert.equal(result.items.find((row) => row.id === 'past')?.mobile, null);
+  });
+
+  it('نام را در متن پیامک می‌گذارد', () => {
+    assert.equal(
+      fillBirthdaySmsText(BIRTHDAY_SMS_DEFAULT, 'آیدا', 'کریمی'),
+      'آیدا کریمی عزیز، تولدتان مبارک.',
+    );
+    assert.equal(fillBirthdaySmsText('  سلام {نام}  ', 'آیدا', ''), 'سلام آیدا');
+  });
+});