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/designs/GlassSurface.dart

@@ -23,7 +23,7 @@ class GlassSurface extends StatelessWidget {
   const GlassSurface({
     super.key,
     required this.child,
-    this.radius = const BorderRadius.all(Radius.circular(20)),
+    this.radius = const BorderRadius.all(Radius.zero),
     this.padding = EdgeInsets.zero,
     this.tint,
     this.onDark = false,
@@ -60,7 +60,7 @@ class GlassSurface extends StatelessWidget {
 Widget glassCircle(
   IconData icon,
   VoidCallback onTap, {
-  double size = 42,
+  double size = 50,
   bool onDark = false,
   bool dotted = false,
   Color? dotColor,
@@ -73,7 +73,7 @@ Widget glassCircle(
       children: [
         GlassSurface(
           onDark: onDark,
-          radius: BorderRadius.circular(size),
+          radius: BorderRadius.zero,
           child: SizedBox(
             width: size,
             height: size,