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/Component.dart

@@ -32,7 +32,7 @@ Widget pill(
     padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 5),
     decoration: BoxDecoration(
       color: background,
-      borderRadius: BorderRadius.circular(999),
+      borderRadius: BorderRadius.zero,
       border: Border.all(color: foreground.withValues(alpha: 0.20), width: 1),
     ),
     child: Row(
@@ -57,7 +57,7 @@ Widget pill(
 /// The standard card surface.
 Widget card({
   required Widget child,
-  EdgeInsets padding = const EdgeInsets.all(16),
+  EdgeInsets padding = const EdgeInsets.all(20),
   EdgeInsets margin = EdgeInsets.zero,
   Color? background,
   Color? borderColor,
@@ -70,7 +70,7 @@ Widget card({
     margin: margin,
     decoration: BoxDecoration(
       color: background ?? colorCard,
-      borderRadius: BorderRadius.circular(radius),
+      borderRadius: BorderRadius.zero,
       border: Border.all(color: borderColor ?? colorGlassBorder, width: 1),
       boxShadow: const [
         BoxShadow(
@@ -159,7 +159,6 @@ Widget emptyState(
             height: 76,
             decoration: BoxDecoration(
               color: tone.withValues(alpha: 0.08),
-              shape: BoxShape.circle,
             ),
             child: Icon(icon, size: 32, color: tone),
           ),
@@ -191,7 +190,7 @@ Widget meter(
               : fraction;
 
   return ClipRRect(
-    borderRadius: BorderRadius.circular(999),
+    borderRadius: BorderRadius.zero,
     child: LinearProgressIndicator(
       value: clamped,
       minHeight: height,