feat: environment widgets layout redesign with always-visible widgets

- Desktop: 4-in-a-row layout (30/20/20/30 distribution)
- Tablet: 2x2 grid layout
- Mobile: Stacked vertically
- All widgets show "No data available" state instead of being hidden
- Sun position calculates from clock, defaults to 6am/6pm
- Environment refresh changed from 5min to 1 hour

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

test/features/front_hall/environment_test.dart

@@ -89,7 +89,8 @@ void main() {
       expect(find.text('Air Quality'), findsOneWidget);
     });
 
-    testWidgets('hides Air Quality widget when no data', (tester) async {
+    testWidgets('shows Air Quality widget with no data state when data unavailable',
+        (tester) async {
       await setLargeWindowSize(tester);
       harness.givenAuthenticatedUser();
       harness.givenQuickLinks();
@@ -99,8 +100,9 @@ void main() {
       await tester.pumpWidget(harness.wrap(const FrontHallPage()));
       await tester.pumpAndSettle();
 
-      // Air Quality widget should not be present
-      expect(find.byType(AirQualityWidget), findsNothing);
+      // Air Quality widget should still be present, showing "no data" state
+      expect(find.byType(AirQualityWidget), findsOneWidget);
+      expect(find.text('Air Quality'), findsOneWidget);
     });
 
     testWidgets('calls environment API on mount', (tester) async {