Adds an owner-authenticated weekly agenda (grouped by day, today highlighted)
with manual walk-in/phone booking creation, cancel, and reschedule -- all
routed through booking_api.py's create/cancel/reschedule logic (refactored
into shared helpers) so the EXCLUDE overlap constraint and confirmation
email stay on the single existing code path. Manual creation can skip the
opening-hours/min-notice/max-advance/buffer checks via an explicit override,
but never the overlap constraint itself.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
