- prefix realtime handoff output with the agent final message label for
both realtime v1 and v2
- update realtime websocket and core expectations to match
## Stack Position
2/4. Built on top of #14828.
## Base
- #14828
## Unblocks
- #14829
- #14827
## Scope
- Port the realtime v2 wire parsing, session, app-server, and
conversation runtime behavior onto the split websocket-method base.
- Branch runtime behavior directly on the current realtime session kind
instead of parser-derived flow flags.
- Keep regression coverage in the existing e2e suites.
---------
Co-authored-by: Codex <noreply@openai.com>
## Stack Position
1/4. Base PR in the realtime stack.
## Base
- `main`
## Unblocks
- #14830
## Scope
- Split the realtime websocket request builders into `common`, `v1`, and
`v2` modules.
- Keep runtime behavior unchanged in this PR.
---------
Co-authored-by: Codex <noreply@openai.com>
