ok: first advance returns 1, got 1
ok: peek now shows next_seq=2, got 2
ok: second advance returns 2, got 2
ok: peek=3 after second, got 3
ok: different business_date starts from 1, got 1
ok: yesterday peek=2
ok: today still at 3 — independent counters
ok: 5 parallel advances = 1..5 (got [1,2,3,4,5])
ok: Asia/Phnom_Penh at 18:00 UTC shows next day, got 2026-04-23
DONE