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/mock/MockMemory.dart

@@ -3,6 +3,7 @@
 import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 
 import '../about/internal/application/MeDescription.dart';
+import '../about/internal/application/TodoItem.dart';
 import '../about/internal/application/UserDetails.dart';
 import '../memory/InternalMemory.dart';
 import 'MockStorage.dart';
@@ -18,6 +19,11 @@ class MockMemory extends InternalMemory {
       setMyDescription(
           MeDescription(id: "mock-user", name: "Alex", token: "mock-token"));
       setUserDetails(UserDetails(pic: "", name: "Alex"));
+      setTodos(<TodoItem>[
+        TodoItem(id: "t1", title: "Refill water bottle"),
+        TodoItem(id: "t2", title: "Book physio for Thursday"),
+        TodoItem(id: "t3", title: "Reply to Sam about Saturday", done: true),
+      ]);
     }
   }