Bootstrap copied BFF and local accounts with public Sendico contracts (#34)

backend/contracts/sendico/models/objectid.yaml

@@ -0,0 +1,9 @@
+components:
+  schemas:
+    ObjectId:
+      description: Object identifier represented as a 24-character hexadecimal string.
+      type: string
+      format: objectid
+      pattern: '^[a-fA-F0-9]{24}$'
+      examples:
+        - 64f85f5f4c7dbf7cfb8f3f10