ci(e2e): add deployment diagnostics step on failure

When the E2E deploy step fails (rollout timeout, pod not ready, etc.),
previously required manual cluster investigation to diagnose the root
cause. This heartbeat had to grep CI logs and query kubectl separately
to determine a :latest image drift issue.

The new step captures pod state, pod describe output, and recent namespace
events immediately when a failure occurs — surfacing the root cause
directly in the CI run log.

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

.github/workflows/e2e.yaml

@@ -72,6 +72,16 @@ jobs:
           HEADLAMP_URL: ${{ env.HEADLAMP_URL }}
           HEADLAMP_TOKEN: ${{ env.HEADLAMP_TOKEN }}
 
+      - name: Collect deployment diagnostics on failure
+        if: failure()
+        run: |
+          echo "=== Pod state ==="
+          kubectl get pods -n "$E2E_NAMESPACE" -l "app.kubernetes.io/instance=$E2E_RELEASE" 2>&1 || true
+          echo "=== Pod describe ==="
+          kubectl describe pods -n "$E2E_NAMESPACE" -l "app.kubernetes.io/instance=$E2E_RELEASE" 2>&1 || true
+          echo "=== Recent namespace events ==="
+          kubectl get events -n "$E2E_NAMESPACE" --sort-by='.lastTimestamp' 2>&1 | tail -20 || true
+
       - name: Teardown E2E instance
         if: always()
         run: scripts/teardown-e2e-headlamp.sh