Frontend first draft

frontend/pshared/lib/models/permissions/effect.dart

@@ -0,0 +1,13 @@
+enum Effect {
+  allow,
+  deny,
+}
+
+extension EffectExtension on Effect {
+  String toShortString() => toString().split('.').last;
+
+  static Effect fromString(String value) => Effect.values.firstWhere(
+    (e) => e.toShortString() == value,
+    orElse: () => throw ArgumentError('Invalid effect: $value'),
+  );
+}