Stream a class straight from a phone

When a class is set up for online streaming, staff opening it in the Business
app now get a clear choice: use the venue's configured camera, pick a camera
for just this occurrence, or stream directly from the phone in their hand.

Phone streaming uses a secure one-time connection created for that single
class, so there are no stream keys to copy or protect. The person streaming
sees their camera preview, connection quality, elapsed time, and a clear End
Stream button; if the phone is lost or swapped mid-setup, the connection can
be revoked and recreated in seconds.

Venue camera setup, permissions, recording preferences, and who may go live
(including the instructor go-live setting) all keep working exactly as
configured. This is rolling out gradually — it appears in the Business app
once enabled for the platform.