feat(F-091): completed feature

work/artifacts/F-091/leader-close.json

@@ -0,0 +1,15 @@
+{
+  "feature_id": "F-091",
+  "agent": "leader",
+  "verdict": "APPROVED",
+  "summary": "F-091 keeps SKU/EAN uniqueness, prevents duplicate in-flight updates, and explains 409 conflicts by field.",
+  "evidence": [
+    "reviewer.json verdict=APPROVED",
+    "security.json verdict=APPROVED",
+    "qa.json verdict=APPROVED",
+    "scripts/verify.sh exit 0",
+    "Root tests: 133 passed, 56 skipped",
+    "Root and admin typechecks exit 0"
+  ],
+  "timestamp": "2026-08-20T19:47:30Z"
+}