Add keepalive pings during job execution to prevent UI timeout desync

The adapter had no mechanism to signal liveness while a K8s Job was
running. When Claude entered long thinking phases with no log output,
the Paperclip UI could lose sync and consider the run stuck even though
the pod was still actively working.

Adds a 15-second interval keepalive that sends status messages via
onLog during execution. The keepalive tracks time since last real log
output and reports it, keeping the connection alive. The timer is
cleaned up in the finally block to prevent leaks on any exit path.

Bumps version to 0.1.11.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@farhoodliquor/paperclip-adapter-claude-k8s",
-  "version": "0.1.10",
+  "version": "0.1.11",
   "description": "Paperclip adapter plugin that runs Claude Code agents as Kubernetes Jobs",
   "license": "MIT",
   "repository": {