fix: forward request_overrides to cron jobs and subagents

[hashbender]

Summary

Forward provider-derived request_overrides through two remaining async paths:

• cron jobs created from an agent session now preserve the runtime provider's request overrides
• delegated subagents inherit parent request overrides unless an explicit provider/runtime override supplies its own request overrides

This keeps custom-provider extra_body / extra_headers behavior consistent for scheduled jobs and delegate_task children.

Why

resolve_runtime_provider() can attach provider-specific request overrides, but cron job creation and subagent construction were dropping them. That means a configured provider can behave correctly in the parent conversation while losing its request overrides in cron/subagent calls.

Prior art / non-duplication check

Related open PRs cover adjacent paths but not these files:

• fix: pass request_overrides to background review and curator agents NousResearch/hermes-agent#56653 covers background review and curator agents
• fix: deliver custom-provider extra_body (request_overrides) on gateway, Open WebUI, and TUI/CLI paths NousResearch/hermes-agent#53765 covers gateway / Open WebUI / TUI / CLI model-switch paths
• fix: preserve named custom provider request_overrides in gateway and /model switches NousResearch/hermes-agent#39429 covers gateway and /model switches

This PR intentionally stays narrow to cron/scheduler.py and tools/delegate_tool.py.

Tests

PYTHONPATH="$PWD" /opt/hermes/.venv/bin/python -m pytest -q -o 'addopts=' \
  tests/cron/test_cron_request_overrides.py \
  tests/tools/test_delegate_request_overrides.py
# 4 passed

PYTHONPATH="$PWD" /opt/hermes/.venv/bin/python -m py_compile \
  cron/scheduler.py \
  tools/delegate_tool.py \
  tests/cron/test_cron_request_overrides.py \
  tests/tools/test_delegate_request_overrides.py

git diff --cached --check

---

Mirror-of: NousResearch#56876
NousResearch#56876