chore: add high level classes

Signed-off-by: The one with the braid <the-one@with-the-braid.cf>

lib/src/models/beacon.dart

@@ -0,0 +1,30 @@
+/// Information about a location beacon.
+class Beacon {
+  /// Unique identifier of a Bluetooth Low Energy location beacon.
+  final String proximityUUID;
+
+  /// Major identifier of a Bluetooth Low Energy location beacon.
+  final double? major;
+
+  /// Minor identifier of a Bluetooth Low Energy location beacon.
+  final double? minor;
+
+  /// Text displayed on the lock screen when the pass is currently relevant.
+  /// For example, a description of the nearby location such as
+  /// “Store nearby on 1st and Main.”
+  final String? relevantText;
+
+  const Beacon({
+    required this.proximityUUID,
+    this.major,
+    this.minor,
+    this.relevantText,
+  });
+
+  factory Beacon.fromJson(Map<String, Object?> json) => Beacon(
+        proximityUUID: json['proximityUUID'] as String,
+        major: json['major'] as double?,
+        minor: json['minor'] as double?,
+        relevantText: json['relevantText'] as String?,
+      );
+}