Square every corner, enlarge the main surfaces and add a to-do list

Rounded rectangles and round controls are now square across the app; only
status dots, glows, the sun, rings and the breathing circle stay round.
Cards, rows, thumbnails, featured cards, category tiles, the standing card
and the nav are larger. Home gets a quick To-do list kept on the device
(TodoItem in InternalMemory), seeded with sample items in mock mode.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KhQh614DMeYoQEH9SoMRUw

frontend/lib/Grounded/about/internal/application/TodoItem.dart

@@ -0,0 +1,27 @@
+/// A quick to-do: no window, no class, no debt. Kept on the device so jotting
+/// something down never waits on the network.
+class TodoItem {
+  String id;
+
+  String title;
+
+  bool done;
+
+  TodoItem({required this.id, required this.title, this.done = false});
+
+  factory TodoItem.fromJson(Map<String, dynamic> json) {
+    return TodoItem(
+      id: json['id'] ?? '',
+      title: json['title'] ?? '',
+      done: json['done'] ?? false,
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    final Map<String, dynamic> data = <String, dynamic>{};
+    data['id'] = id;
+    data['title'] = title;
+    data['done'] = done;
+    return data;
+  }
+}