fix(kimi-code): exit 1 when a headless (-p) turn fails (#1483)

Headless (`kimi -p`) failures could exit with code 0 when the event loop
drained during the shutdown cleanup (e.g. telemetry's unref'd retry backoff
when the network is blocked), because the rejection never reached the
process.exit(1) call. Set the failure exit code before any await in both
the run-prompt catch and the main catch, and keep the cleanup timeout ref'd
so the loop stays alive long enough for the rejection to propagate.

.changeset/fix-headless-exit-code.md

@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+Fix `kimi -p` runs exiting with code 0 when a turn fails.