fix: replace mktemp with PID-based temp path for BusyBox compat

BusyBox mktemp in alpine/k8s doesn't support .json suffix in template.
The mktemp failure triggered set -e, causing pipeline to report failure
despite all 93 tests passing.

infra/inttest/run_pipeline.sh

@@ -456,7 +456,7 @@ if [ -n "$RUNNER_POD" ]; then
   kubectl logs "$RUNNER_POD" -n "$NAMESPACE" 2>/dev/null || true
 
   # Try to copy profiling report
-  PROFILING_TMP=$(mktemp /tmp/profiling-report-XXXXXX.json)
+  PROFILING_TMP="/tmp/profiling-report-$$.json"
   if kubectl cp "$NAMESPACE/$RUNNER_POD:/tmp/profiling-report.json" "$PROFILING_TMP" 2>/dev/null; then
     log "Profiling report collected"
     PROFILING_JSON="$PROFILING_TMP"