Replace two inline copies of the env/config model resolution pattern
(in _run_agent_sync and _run_agent) with the _resolve_gateway_model()
helper introduced in PR #830.
Left untouched:
- Session hygiene block: different default (sonnet vs opus) + reads
compression config from the same YAML load
- /model command: also reads provider from same config block
teknium1
01bec40724