Add a dedicated client first-message timeout while preserving the legacy 30-second default.
Use the resolved value for both the WebSocket read deadline and structured timeout logs, and document tuning for large requests or slow links.
Add configuration, validation, handler, and resolver regression coverage.
Refs #4158
The hardcoded codex CLI version (0.104.0) causes upstream rejection
when using gpt-5.5 with compact, as the server treats the request
as an outdated client and returns 400/502.
Update codexCLIVersion, codexCLIUserAgent, and openAICodexProbeVersion
to 0.125.0 to match the current Codex CLI release.
Fixes#1933, #1887, #1865
Related: #1609, #1298, #849
Tiantianr