feat: add temp storage shelf (B prefix) UI support

Recognize B-prefix location codes as temp storage shelves. Add purple
color scheme, conflict detection for temp_stored status, and updated
submit/dialog logic for temp storage target handling.

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

lib/pages/registration/registration_calculations.dart

@@ -5,11 +5,13 @@ class RegistrationOverviewStats {
   final int totalCount;
   final int shelvedCount;
   final int transferredCount;
+  final int tempStoredCount;
 
   const RegistrationOverviewStats({
     required this.totalCount,
     required this.shelvedCount,
     required this.transferredCount,
+    required this.tempStoredCount,
   });
 }
 
@@ -31,17 +33,21 @@ RegistrationOverviewStats overviewStats(PaichaOverviewResult? overview) {
       totalCount: 0,
       shelvedCount: 0,
       transferredCount: 0,
+      tempStoredCount: 0,
     );
   }
 
   var shelvedCount = 0;
   var transferredCount = 0;
+  var tempStoredCount = 0;
   for (final item in overview!.items) {
     switch (item.status) {
       case 'on_shelf':
         shelvedCount++;
       case 'transferred':
         transferredCount++;
+      case 'temp_stored':
+        tempStoredCount++;
     }
   }
 
@@ -49,6 +55,7 @@ RegistrationOverviewStats overviewStats(PaichaOverviewResult? overview) {
     totalCount: overview.totalCount,
     shelvedCount: shelvedCount,
     transferredCount: transferredCount,
+    tempStoredCount: tempStoredCount,
   );
 }
 
@@ -91,6 +98,17 @@ List<PaichaOverviewItem> findTransferredItemsInScanned({
   );
 }
 
+List<PaichaOverviewItem> findTempStoredItemsInScanned({
+  required PaichaOverviewResult? overview,
+  required Iterable<String> zongpaiNos,
+}) {
+  return _findScannedItemsByStatus(
+    overview: overview,
+    zongpaiNos: zongpaiNos,
+    status: 'temp_stored',
+  );
+}
+
 bool hasAnyLocatedInScanned({
   required PaichaOverviewResult? overview,
   required Iterable<String> zongpaiNos,
@@ -100,7 +118,9 @@ bool hasAnyLocatedInScanned({
   return overview!.items.any(
     (item) =>
         scannedSet.contains(item.zongpaiNo) &&
-        (item.status == 'on_shelf' || item.status == 'transferred'),
+        (item.status == 'on_shelf' ||
+            item.status == 'transferred' ||
+            item.status == 'temp_stored'),
   );
 }
 
@@ -108,10 +128,13 @@ Color registrationBarColor({
   required String status,
   required bool isScanned,
   required bool isTransitTarget,
+  bool isTempStorageTarget = false,
 }) {
   if (isScanned) {
     final isConflict = isTransitTarget
         ? status == 'transferred'
+        : isTempStorageTarget
+        ? (status == 'transferred' || status == 'temp_stored')
         : (status == 'on_shelf' || status == 'transferred');
     return isConflict ? Colors.red : const Color(0xFF43A047);
   }
@@ -119,6 +142,8 @@ Color registrationBarColor({
   switch (status) {
     case 'on_shelf':
       return const Color(0xFF2196F3);
+    case 'temp_stored':
+      return const Color(0xFF7B1FA2);
     case 'transferred':
       return const Color(0xFFFF9800);
     default:
@@ -130,10 +155,13 @@ Color registrationRowBgColor({
   required String status,
   required bool isScanned,
   required bool isTransitTarget,
+  bool isTempStorageTarget = false,
 }) {
   if (isScanned) {
     final isConflict = isTransitTarget
         ? status == 'transferred'
+        : isTempStorageTarget
+        ? (status == 'transferred' || status == 'temp_stored')
         : (status == 'on_shelf' || status == 'transferred');
     return isConflict ? Colors.red.shade50 : const Color(0xFFF1F8E9);
   }
@@ -141,6 +169,8 @@ Color registrationRowBgColor({
   switch (status) {
     case 'on_shelf':
       return const Color(0xFFE3F2FD);
+    case 'temp_stored':
+      return const Color(0xFFF3E5F5);
     case 'transferred':
       return const Color(0xFFFFF3E0);
     default: