Fix vertical overflow by removing nested Scaffold architecture

- Remove nested Scaffold from ScoringPage (now uses LayoutBuilder)
- Use proper constraint-based height calculation instead of MediaQuery
- Maintain score preservation across navigation without nested scaffolds
- Fix viewport architecture to work within MainNavigationPage body
- Minor keypad layout adjustment (77%/23% flex ratio)

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

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

lib/presentation/pages/main_navigation_page.dart

@@ -123,7 +123,7 @@ class _MainNavigationPageState extends State<MainNavigationPage> {
             const Padding(
               padding: EdgeInsets.all(16.0),
               child: Text(
-                'Professional archery scoring with sophisticated end interaction system.',
+                'REPLACE ALL THESE TEXTS WITH LOCALISATION MARKERS!!',
                 style: TextStyle(
                   fontSize: 12,
                   color: Colors.grey,