Tapping a day tile puts it in the swapping state and opens a bottom sheet
segmented "Quest log · N | Regulars · N". Choosing a dinner swaps the day
optimistically with PUT /api/v1/plans/{weekStart}/days/{date}, landing the
server's plan on success and rolling the day back with an ErrorBanner and
Retry on failure. Dinners already this week are marked and not selectable.
Maestro task f231813c-992e-4a3b-a1a4-868cbad47415.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>