Stream live waits (Server-Sent Events)

A text/event-stream of the same messages as the WebSocket for one park: snapshot first, then changes and park events as they happen (the server checks every 5 seconds and pushes a ride only when Disney or Universal changes it; posted waits typically change every few minutes), and a : ping comment line every 25 seconds. Each event is a single data: line holding one JSON message; there are no event: names, so EventSource.onmessage receives everything. Browsers may authenticate with ?key=. A failed upstream refresh sends an error and ends the stream; EventSource reconnects after its 5-second retry delay. Keyed streams also end at the cached key verdict expiry (at most 10 minutes); reconnect to revalidate. Counts once against the per-minute limit when it connects. Returns 403 rights_unavailable when the server has provider-derived data disabled.