6bd1726422
Allow users to configure a dedicated model for subagents spawned by
delegate_task, so narrowly-scoped subtasks can use a cheaper/faster
model while the parent agent runs on a more powerful one.
Config:
subagent:
model: google/gemini-3-flash-preview
Precedence: explicit model arg > config.subagent.model > parent model.
Cherry-picked from PR #751 by Bartok9, rebased onto current main
with conflict resolution and simplified to model-only override
(provider/base_url/api_key stay inherited from parent — covers the
common case of same-provider model swap via OpenRouter).
Closes #609
Co-authored-by: Bartok Moltbot <bartokmoltbot@users.noreply.github.com>