Adds the three proposal fields (proposed_target_date, proposed_by,
proposed_at) to the cards collection with a partial index that backs
the 'pending proposals' query, plus two new ActivityAction values
(date_proposed, date_proposal_resolved) and column_changed for
return-to-scheduled.
New server actions under src/app/actions/:
- client-proposal.ts: client-manager drag creates a proposal (not
a target_date write); 404 (not 403) on cross-tenant failures and
Done-column cards, matching the rest of /api/client/*.
- owner-plan.ts: accept and dismiss clear the three proposal
fields together and emit the audit rows; returnToScheduledAction
moves a Done card back to the first working column.
Server-side Done-column guards added to:
- src/app/actions/reschedule.ts (was UI-only)
- src/app/api/client/cards/[id]/route.ts (was UI-only)
Both pass through the new writeCardWithAudit helper at
src/lib/cards/write-with-audit.ts — single source of truth for
'patch card + emit activity rows', replacing the inline copies in
the PATCH route and rescheduleCardAction.
Adds src/lib/roadmap/slot-date.ts (slot <-> target_date mapping)
consumed by Pixel's puzzle UI; named SlotId API rather than the
plan's numeric indices for self-documenting callers.
CLIENT_EDITABLE_CARD_FIELDS stays at priority + target_date per
the brief; proposals go through the dedicated action so they get
their own audit row type.
