feat: add tool timeouts to prevent gh CLI hangs

[ichoosetoaccept]

FastMCP 3.0 adds tool timeouts. We should configure timeouts on our tools to prevent indefinite hangs when gh CLI calls stall (network issues, GitHub API outages).

What's available:

• Tool-level timeout configuration
• Sync functions auto-dispatch to threadpool

Value: Prevents agent sessions from hanging when GitHub API is slow or unresponsive. Our gh CLI calls are the primary bottleneck.

Ref: https://github.com/PrefectHQ/fastmcp/releases/tag/v3.0.0