feat(agent-pod): add agent-hub sidecar for multi-agent session monitoring

Hub relays pi's own --mode json session protocol (session/agent_start/
turn_start/message_*/turn_end/agent_end -- the same event shape Claude
Code sessions use) to agent-console over WebSocket, so concurrent pi
runs inside the pod are observable as real transcripts instead of log
tails. agent-run.js wraps `pi -p --mode json` and relays its stdout
lines to the hub; each invocation gets its own session id, so N
concurrent agents show up as N sessions. Source mounted via ConfigMap
and run with `go run .` (no registry yet, same as the pi container).

k8s/apps/agent-pod/hub-service.yaml

@@ -0,0 +1,11 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: agent-hub
+  namespace: agent-pod
+spec:
+  selector:
+    app: agent-pod
+  ports:
+    - port: 9090
+      targetPort: 9090