add transfer all button for admins

lib/ui/app_shell.dart

@@ -200,6 +200,22 @@ class _MyAppState extends State<MyApp> {
                     (state.extra is Map
                         ? (state.extra as Map)['transferFromLabel']?.toString()
                         : null);
+                bool transferAllAllocations = false;
+                final transferAllParam =
+                    state.uri.queryParameters['transferAll'] ??
+                        (state.extra is Map
+                            ? (state.extra as Map)['transferAll']?.toString()
+                            : null);
+                if (transferAllParam != null) {
+                  transferAllAllocations = transferAllParam.toLowerCase() == 'true' ||
+                      transferAllParam == '1';
+                }
+                if (!transferAllAllocations && state.extra is Map) {
+                  final raw = (state.extra as Map)['transferAll'];
+                  if (raw is bool) {
+                    transferAllAllocations = raw;
+                  }
+                }
                 final selectionMode =
                     (selectionParam != null && selectionParam.isNotEmpty) ||
                         replacementPendingLocoId != null ||
@@ -215,6 +231,7 @@ class _MyAppState extends State<MyApp> {
                   replacementPendingLocoId: replacementPendingLocoId,
                   transferFromLabel: transferFromLabel,
                   transferFromLocoId: transferFromLocoId,
+                  transferAllAllocations: transferAllAllocations,
                 );
               },
             ),