Show core.event's fixed status values on the Event page #695

Summary

core.event's status is now a fixed list of values: tentative, confirmed and canceled (withmarfa/marfa#2483). Any other value is refused. The Event page still describes it as free text with recommended values, including rescheduled, which Marfa no longer accepts. After this change, the docs show the three values and say what the field means.

Context

Checked at docs main today:

• The Event page's field table comes from src/generated/catalog/core.event.md, written by the sync script. It shows status as string, "Recommended values: tentative, confirmed, canceled, rescheduled".
• The Google Calendar page names confirmed and tentative, which stay valid.

Acceptance criteria

• The sync from marfa at or after feat(types): make core.event status a fixed list of values marfa#2483 runs, and its pull request merges.
• The Event page shows status as enum with tentative, confirmed and canceled.
• The Event page says, in a sentence near the table, that status says whether the event will happen, and that moving an event changes its time, not its status.
• No page names rescheduled as an event status.

Out of scope

• Status groups for tasks, which are a separate change.