feat(admin): events & sessions

[cdcore09]

Summary

Event lifecycle management — creation, approval, committee assignment, session scheduling, attendance tracking, sponsor wiring. Largest subsystem. Likely needs decomposition into sub-issues during its own brainstorm.

Requirements

• Brainstorming → spec under docs/superpowers/specs/. (Likely splits into 2–3 sub-specs.)
• /admin/events — global list (staff+); event chairs see only events they chair.
• Event creation flow: draft → submitted → approved → published, with status enum and approval gate.
• /admin/events/:id — detail editor: dates, location, description, type, links.
• Committee management: assign chairs / co-chairs / area leads via event_committee_assignments.
• Session scheduling: CRUD on event_sessions, presenter assignment via event_session_presenters, session_type selection.
• Attendance: import / record event_attendances rows with role (attendee, speaker, organizer, sponsor, volunteer).
• Sponsor wiring: link event_sponsorships to each event (depends on feat(admin): organizations — logos, memberships, sponsorships #1959 organizations).

Context

Foundation must ship first (#1956). Schema already supports nearly all of this — events, event_committee_areas, event_committee_assignments, event_sessions, event_session_types, event_session_presenters, event_attendances. Lots of UI work, modest schema additions.

Implementation Notes

• Policy: canEditEvent(actor, { eventId }) — staff+ OR chairedEventIds.has(eventId).
• "Approval" workflow is one of the few places we need a real status state machine; design carefully during its brainstorm.
• This subsystem likely couples to Communications (feat(admin): elections #1964) for attendee notifications — flag the dependency during brainstorm.