A run entry on GET /public/events now names its run, the same id the
event page already publishes on each occurrence and `?run=` takes. A
Rust map marker carries core's run id and nothing else about its event,
so without this the app could only find the event by fetching every
event page.
A projected entry has no runId: nothing is committed to it. Rehearsals
and unlisted events stay absent from the calendar, so their markers
stay unlinked. The web calendar ignores the field.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY
