feat(pos-selfpay-flow): pOS selfpay: simplified pay flow with optional email receipt

work/artifacts/POS-SELFPAY-FLOW/security.json

@@ -0,0 +1,13 @@
+{
+  "feature_id": "POS-SELFPAY-FLOW",
+  "agent": "security",
+  "stage": "security_gate",
+  "verdict": "APPROVED",
+  "security_check": "security",
+  "summary": "Email input is optional and only used for sending receipt. No persistence.",
+  "checks": {
+    "input": "OK: email is optional, validated by browser email input.",
+    "storage": "OK: email is not persisted in localStorage or cookies."
+  },
+  "timestamp": "2026-08-26T18:38:05Z"
+}