feat(ipc): configure entrypoint shutdown timeout

[tmtcam-042]

Summary

The job process currently waits for the entrypoint for a hard-coded 15 seconds during shutdown before cancelling it. This makes that grace period configurable through ServerOptions and AgentServer while preserving the existing 15-second default.

Setting entrypoint_shutdown_timeout=0.0 cancels the entrypoint immediately, allowing applications to terminate active calls without waiting for voice playout or other entrypoint work to drain. Shutdown callbacks continue to run after cancellation.

Closes #6512.

Changes

• add entrypoint_shutdown_timeout to ServerOptions, AgentServer, and update_options
• pass the setting through ProcPool to process and thread job executors
• use the configured timeout when waiting for the job entrypoint during shutdown
• cover the default, option forwarding, updates, and immediate-cancellation behavior

Testing

• uv run pytest tests/test_ipc.py tests/test_worker_config.py --unit -q — 26 passed
• make check — formatting, Ruff, and mypy passed across all 623 source files

[CLAassistant]

All committers have signed the CLA.

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.