isReminderDue now keys off doc.remindersDisabled and the effective
cadence (per-doc override → template default), dropping the implicit
interests.reminderEnabled gate so non-EOI docs auto-remind correctly.
sendReminderIfAllowed gains an options bag — auto:true keeps the 9-16
window + cadence cooldown for the cron, auto:false bypasses both for
manual UI sends. signerId targets a specific pending signer (must be
next in sequential mode). 7 unit tests cover the cadence math.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>