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/FloatingNav.dart

@@ -36,7 +36,7 @@ class FloatingNav extends StatelessWidget {
             Expanded(
               child: Container(
                 decoration: BoxDecoration(
-                  borderRadius: BorderRadius.circular(34),
+                  borderRadius: BorderRadius.zero,
                   boxShadow: const [
                     BoxShadow(
                       color: Color(0x1A1A1F1C),
@@ -46,7 +46,7 @@ class FloatingNav extends StatelessWidget {
                   ],
                 ),
                 child: GlassSurface(
-                  radius: BorderRadius.circular(34),
+                  radius: BorderRadius.zero,
                   tint: colorGlassStrong,
                   padding: const EdgeInsets.all(6),
                   child: Row(
@@ -62,10 +62,9 @@ class FloatingNav extends StatelessWidget {
             GestureDetector(
               onTap: onAction,
               child: Container(
-                width: 64,
-                height: 64,
+                width: 72,
+                height: 72,
                 decoration: BoxDecoration(
-                  shape: BoxShape.circle,
                   gradient: const RadialGradient(
                     center: Alignment(-0.3, -0.4),
                     colors: <Color>[colorNightGlow, colorNight],
@@ -98,7 +97,7 @@ class FloatingNav extends StatelessWidget {
         padding: const EdgeInsets.symmetric(vertical: 9),
         decoration: BoxDecoration(
           color: active ? colorWhite : colorWhite.withValues(alpha: 0.0),
-          borderRadius: BorderRadius.circular(28),
+          borderRadius: BorderRadius.zero,
           boxShadow: active
               ? const [
                   BoxShadow(
@@ -113,7 +112,7 @@ class FloatingNav extends StatelessWidget {
           mainAxisSize: MainAxisSize.min,
           children: [
             Icon(entry.icon,
-                size: 19, color: active ? colorInk : colorInkSoft),
+                size: 23, color: active ? colorInk : colorInkSoft),
             const SizedBox(height: 4),
             text(entry.label, 10, active ? TextType.Medium : TextType.Regular,
                 color: active ? colorInk : colorInkSoft, maxLines: 1),