Reminders used to fire whenever the hourly ticker happened to scan after
a user's first eligible event — m got mail at 02:28. We now gate delivery
to a user-chosen hour-of-day in their local timezone.
* Migration 022 adds reminder_morning_time / reminder_evening_time /
reminder_timezone (defaults 09:00, 16:00, Europe/Berlin).
* New "due_today_evening" reminder kind with its own template — fires only
for due_date = today AND status = pending, in the evening slot.
* Reminder service computes user-local hour each tick and skips users
outside their slot. SQL widens to a 3-day band; in-process filter
narrows to per-user local date.
* Settings → Notifications gains time inputs and a timezone field.
* Tests: pure (inSlot, slotForKind, matchesLocalDueDate) plus a live-DB
TestReminderSlots covering morning, evening, outside-slot, and the
completed-deadline case.
