feat(events): numeric code check-in

[danielhe4rt]

Parent

#237

What to build

Implement numeric code check-in: organizer generates a short-lived code bound to a specific date, participant enters it to check in. Also supports bot-triggered check-in via domain events.

Admin panel — Code management:

• "Generate Check-in Code" action on Event resource
• Fields: code (auto-generated or manual), event_date, valid_from, valid_until, max_uses (optional)
• List of active/expired codes per event with usage stats
• Code format: 4-6 digit numeric string

Extend CheckInAction (numeric_code path):

• Validates: code exists for this event + event_date
• Validates: now() BETWEEN valid_from AND valid_until
• Validates: uses_count < max_uses (if max_uses is not null)
• Atomically increments uses_count on the code record
• Creates check-in record with method=numeric_code, payload={code: "4829"}
• Same enrollment status transition logic as manual (confirmed → checked_in on first, record-only on subsequent)
• Dispatches ParticipantCheckedIn

App panel — Code entry:

• "Enter Check-in Code" form visible when enrollment is confirmed or checked_in (multi-day)
• Input field for the numeric code
• Validation errors: "Code expired", "Code already used maximum times", "Invalid code for today"
• Success confirmation on valid check-in

Error handling:

• Invalid code: 422 with "Invalid check-in code"
• Expired code (valid_until passed): 422 with "Code has expired"
• Exhausted code (uses_count >= max_uses): 422 with "Code has reached maximum uses"
• Wrong date (code is for a different event_date): 422 with "Code is not valid for today"

Acceptance criteria

• Organizer can generate numeric codes bound to a specific event date
• Participant can enter code in App panel and get checked in
• Code validation checks: existence, date match, time window, max uses
• uses_count is incremented atomically on successful check-in
• Expired/exhausted codes are rejected with clear error messages
• Multi-day: participant can use different codes on different days
• Check-in record stores method=numeric_code with code in payload
• ParticipantCheckedIn domain event dispatched
• Feature tests: valid code, expired code, exhausted code, wrong date, concurrent usage
• Pint passes

Blocked by

• feat(events): RSVP enrollment end-to-end #240 (RSVP Enrollment — needs confirmed enrollments)