Availability / RSVP flow for club nights

[aamcatamney]

Problem

Pegboard sessions are populated by the host adding attendees on the night. There's no way for players to signal availability beforehand, so the host can't plan numbers or pre-fill the board.

⚠️ Domain constraints — read before scoping

• Players are not login accounts (CONTEXT.md Player: "A Player is not a login account"). RSVP therefore can't be a logged-in player action. Options:
  • (a) Tokenised self-serve — a per-player login-free link (cf. the iCal feed token) to a public RSVP page marking going / maybe / out.
  • (b) Admin-entered — the host/admin records availability on behalf of players.
• A Pegboard Session today is Open → Closed with no future/scheduled state (CONTEXT.md Pegboard Session). RSVP implies a planned/upcoming session with a date before it's opened — that concept needs adding first.

Sketch

• A scheduled-session concept (a date + status Planned) ahead of Open.
• RSVP records (roster player or guest → status) against a planned session.
• On opening the board, pre-fill attendees from RSVPs.

Open questions

• Self-serve tokenised (a) vs admin-entered (b)?
• Add scheduled/future sessions first (likely a prerequisite)?