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/services/registration_linking.dart

@@ -8,13 +8,20 @@ bool isTransitTarget(CodeType? locationType, String? locationCode) {
       (locationCode?.startsWith('TRANS-') ?? false);
 }
 
+bool isTempStorageTarget(CodeType? locationType, String? locationCode) {
+  return locationType == CodeType.locationTempStorage ||
+      (locationCode?.startsWith('B') ?? false);
+}
+
 String registrationSubmitLabel({
   required bool isTransitTarget,
   required bool isMultiCode,
   required int zongpaiCount,
 }) {
   if (!isTransitTarget) {
-    return isMultiCode && zongpaiCount > 1 ? '批量上架（$zongpaiCount 条）' : '确 认 上 架';
+    return isMultiCode && zongpaiCount > 1
+        ? '批量上架（$zongpaiCount 条）'
+        : '确 认 上 架';
   }
   return isMultiCode && zongpaiCount > 1 ? '批量转运并凑箱（$zongpaiCount 条）' : '转运并装箱';
 }