added guardian letters with chat and multiple answer functionalities

lib/utils/random_id.dart

@@ -8,3 +8,12 @@ String randomHexId({int bytes = 16}) {
     (_) => random.nextInt(256),
   ).map((b) => b.toRadixString(16).padLeft(2, '0')).join();
 }
+
+/// Random RFC 4122 version-4 UUID, for ids a server expects in UUID form.
+String randomUuidV4() {
+  final hex = randomHexId();
+  final variant = (int.parse(hex[16], radix: 16) & 0x3 | 0x8).toRadixString(16);
+  return '${hex.substring(0, 8)}-${hex.substring(8, 12)}-'
+      '4${hex.substring(13, 16)}-$variant${hex.substring(17, 20)}-'
+      '${hex.substring(20)}';
+}