feat: support box-number navigation for completed multi-code boxing & unify key handling

- In multi-code boxing mode, scanning a completed total-row number shows a
  clickable warning banner; clicking it or pressing P4 navigates to that
  box number to view boxing details.
- Unify key handling across all pages to LogicalKeyboardKey named constants,
  removing the _androidKeyCodeFromLogicalKey fallback path.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/pages/home_page.dart

@@ -39,10 +39,6 @@ class HomePage extends StatefulWidget {
 }
 
 class _HomePageState extends State<HomePage> {
-  static const _androidKeyCode1 = 8;
-  static const _androidKeyCode2 = 9;
-  static const _androidKeyCode3 = 10;
-
   final _apiService = ApiService();
   final _focusNode = FocusNode();
   bool _isCheckingConnection = false;
@@ -134,23 +130,6 @@ class _HomePageState extends State<HomePage> {
         event.character == '3') {
       return 3;
     }
-
-    // Android keyCode fallback for scanner devices: 1/2/3 => 8/9/10.
-    final androidKeyCode = _androidKeyCodeFromLogicalKey(key);
-    return switch (androidKeyCode) {
-      _androidKeyCode1 => 1,
-      _androidKeyCode2 => 2,
-      _androidKeyCode3 => 3,
-      _ => null,
-    };
-  }
-
-  int? _androidKeyCodeFromLogicalKey(LogicalKeyboardKey key) {
-    final keyId = key.keyId;
-    const androidPlane = LogicalKeyboardKey.androidPlane;
-    if (keyId >= androidPlane && keyId < androidPlane + 0x100000000) {
-      return keyId - androidPlane;
-    }
     return null;
   }