Adds two integer columns to the reminders table:
* delivery_window_start_hour (default 6)
* delivery_window_end_hour (default 18)
Both are documented in the operator's timezone. End hour will gate
the runtime fire-reminder loop in a later phase; this commit just
lands the data model and the pure window-end calculator.
windowEndAt(timezone, endHour, fireAt) lives in @cmbot/shared so
both bot (window enforcement) and web (ETA preview) can import it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
yiekheng
7039d57a41