Port of #46542 by @MarkVLK onto current main:
- hermes_cli/runtime_provider.py: _copilot_runtime_api_mode must not veto
a stale configured codex_responses mode for chat-only Copilot models;
recompute from the live model capabilities.
- agent/transports/codex.py: request summary:"auto" on the GitHub
Responses API so reasoning summaries surface.
- agent/agent_init.py: recompute api_mode at init-time fallback so the
fallback provider/model gets its own mode (and the primary-runtime
snapshot reflects it).
- tests: regression tests for the stale-mode veto, the GitHub Responses
summary, and the init-time fallback recompute.
Conflicts resolved against main's refactored fallback ladder
(agent/chat_completion_helpers.py) and its expanded transport tests.
Co-authored-by: Mark Vlcek <markvlcek@gmail.com>
Fixes#46527
