add pinned event and server ACL diffing

lib/helpers/extensions/success_scheme.dart

@@ -0,0 +1,11 @@
+import "package:dynamic_color/dynamic_color.dart";
+import "package:material_ui/material_ui.dart";
+
+extension SuccessScheme on ThemeData {
+  /// Green colors for positive things, like accepting knocks or new pins,
+  /// harmonized so they fit the current theme.
+  ColorScheme get successScheme => ColorScheme.fromSeed(
+    seedColor: Colors.green.harmonizeWith(colorScheme.primary),
+    brightness: brightness,
+  );
+}