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>

pubspec.yaml

@@ -1,5 +1,5 @@
-name: archery_bookkeeper
-description: "Archery scoring companion."
+name: archery_scorer
+description: "Archery scorer - A Flutter application."
 # The following line prevents the package from being accidentally published to
 # pub.dev using `flutter pub publish`. This is preferred for private packages.
 publish_to: 'none' # Remove this line if you wish to publish to pub.dev