Initial commit: AS4/411 directory and discovery service for Sankofa Marketplace

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/protocols/test-vectors/iso20022-as4/negative-unknown-identifier.json

@@ -0,0 +1,16 @@
+{
+  "description": "Unknown BIC/LEI: no match. Response must have no primary (or empty directives) and negative_cache_ttl set.",
+  "request": {
+    "identifiers": [
+      { "type": "as4.partyId", "value": "UNKNOWNBICXXX", "scope": "BIC" }
+    ],
+    "serviceContext": {
+      "service": "iso20022.fi",
+      "action": "credit.transfer"
+    }
+  },
+  "expectedResponse": {
+    "directives": [],
+    "negative_cache_ttl": 60
+  }
+}