feat(F-091): completed feature

work/artifacts/F-091/qa.json

@@ -0,0 +1,14 @@
+{
+  "feature_id": "F-091",
+  "agent": "qa",
+  "verdict": "APPROVED",
+  "summary": "Variant conflict handling and duplicate-submit protection pass the complete available checks.",
+  "evidence": [
+    "Root npm run typecheck exit 0",
+    "Root npm test: 133 passed, 56 skipped",
+    "Admin npx tsc --noEmit exit 0",
+    "Admin ESLint on InventorySection exit 0",
+    "scripts/verify.sh exit 0"
+  ],
+  "timestamp": "2026-08-20T19:47:20Z"
+}