- track.js captures first-touch source per session (utm_source/src param
or external referrer domain) and logs bridge/start page views.
- Join clicks now carry the source; all events aggregate per-source in
data/analytics.json on the persistent volume.
- Admin: new Traffic & Conversions card with funnel totals (bridge ->
start -> join click rates) and a per-source breakdown table.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>