Summary:
- parse the realtime call Location header and join that call over the
direct realtime WebSocket
- keep WebRTC starts alive on the existing realtime conversation path
Validation:
- just fmt
- git diff --check
- cargo check -p codex-api
- cargo check -p codex-core --tests
- local cargo tests not run; relying on PR CI
Adds WebRTC startup to the experimental app-server
`thread/realtime/start` method with an optional transport enum. The
websocket path remains the default; WebRTC offers create the realtime
session through the shared start flow and emit the answer SDP via
`thread/realtime/sdp`.
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Co-authored-by: Codex <noreply@openai.com>
Ahmed Ibrahim