fix: tie pool submissions to server lifecycle context

Fix 1 (server.go): Replace context.Background() with s.ctx in
handleAnswerQuestion, handleResumeTimedOutTask, and handleRunTask.
Add a ctx field to Server (defaulting to context.Background()) and
a SetContext method so the serve command can wire in the signal-
cancellable lifecycle context.

Fix 2 (serve.go): Call srv.SetContext(ctx) before StartHub so all
pool submissions use the server's root context (already cancelled
on SIGTERM/SIGINT). Pool.Shutdown and its wiring were already present.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions