feat: add Auto Check MH Payment toggle with weekly schedule

Adds a toggle behind the Go button on the Payments page to automatically run the MH batch payment check on a user-selected day of week and hour. Default is off.

- Schema: added autoMhCheckEnabled, autoMhCheckDayOfWeek, autoMhCheckHour to User model
- Backend: new mhBatchPaymentService (shared logic), GET/PUT /auto-mh-check-setting routes, hourly cron job that fires on matching day+hour
- Frontend: toggle + day select (Mon–Sun) + time select (hourly) that persist immediately to DB

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/db/generated/prisma/schema.prisma

@@ -26,6 +26,9 @@ model User {
   autoBackupHour       Int                   @default(20)
   usbBackupEnabled     Boolean               @default(false)
   usbBackupHour        Int                   @default(21)
+  autoMhCheckEnabled   Boolean               @default(false)
+  autoMhCheckDayOfWeek Int                   @default(1)
+  autoMhCheckHour      Int                   @default(13)
   patients             Patient[]
   appointments         Appointment[]
   staff                Staff[]