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/see/settings/SettingsState.dart

@@ -93,8 +93,8 @@ class SettingsState extends State<Settings> implements ConnectSettings {
             decoration: BoxDecoration(
               color: colorSheetBackground,
               borderRadius: const BorderRadius.only(
-                topLeft: Radius.circular(28),
-                topRight: Radius.circular(28),
+                topLeft: Radius.zero,
+                topRight: Radius.zero,
               ),
             ),
             child: SingleChildScrollView(
@@ -112,7 +112,7 @@ class SettingsState extends State<Settings> implements ConnectSettings {
                         margin: const EdgeInsets.only(bottom: 20),
                         decoration: BoxDecoration(
                           color: colorGrey.withValues(alpha: 0.35),
-                          borderRadius: BorderRadius.circular(999),
+                          borderRadius: BorderRadius.zero,
                         ),
                       ),
                     ),
@@ -222,7 +222,7 @@ class SettingsState extends State<Settings> implements ConnectSettings {
                     color: _amnestyRemaining > 0
                         ? colorStandingGoodBg
                         : colorMuted,
-                    borderRadius: BorderRadius.circular(14),
+                    borderRadius: BorderRadius.zero,
                   ),
                   child: Icon(
                     CupertinoIcons.checkmark_shield_fill,