Introduces the HTTP surface the browser (or OBS WebRTC clients)
target when subscribing to a process's egress:
POST /whep/:id -> answer SDP + Location header
DELETE /whep/:id/:resource -> tear down a specific peer
The handler looks up the per-process stream pair via the Subsystem,
validates SDP offer shape, and delegates peer creation to the core
PeerFactory's CreatePeerFromSources (two-source forwarding).
WHEP routes are left unauthenticated in M2 — browsers and OBS don't
carry the Core JWT, and per-process signed-URL tokens are an M3
enhancement. Deployments should place the endpoint behind an
authenticated reverse-proxy for now.
Tests cover:
- 404 for POSTs against unregistered streams
- 400 for empty/invalid SDP offers once a stream is registered
- 404 for DELETE against unknown resource ids
