Propagate graceful-suspend signals through detached run contexts and let
only opt-in suspendable tools re-attach cancellation, so AsTool sub-agents
can checkpoint and restore across nested trees while leaf tools keep
running detached.
Add focused agent and worker tests for single and multi-level suspend/
restore flows, plus heartbeat lease-loss and nested-restore error paths to
harden functional behavior under failure conditions.
Signed-off-by: Bryan Frimin <bryan@probo.com>
0a1b47607b