Add a Reminders subsystem to rSchedule that lets users create date-based
reminders (free-form or linked to cross-module items), receive email
notifications via the existing tick loop, and sync bidirectionally with
rCal calendar events. Includes drag-and-drop from rWork task cards onto
calendar day cells to create reminders.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
