feat: add cross-run finding regression detection

skills/run/SKILL.md

@@ -583,6 +583,14 @@ If `CYCLE >= MAX_CYCLES` and issues remain:
 ./lib/archeflow-event.sh "$RUN_ID" run.complete act "" \
   '{"status":"completed","cycles":<N>,"agents_total":<count>,"fixes_total":<count>,"shadows":0,"artifacts":[<list>]}'
 
+# Check for regressions from previously fixed findings
+if ./lib/archeflow-memory.sh regression-check ".archeflow/events/${RUN_ID}.jsonl"; then
+  echo "No regressions detected."
+else
+  echo "WARNING: Regressions detected — previously fixed findings have reappeared."
+  echo "Review the regression output above and consider addressing them."
+fi
+
 # Generate report
 ./lib/archeflow-report.sh .archeflow/events/${RUN_ID}.jsonl