Pass through all extraneous tags on an existing node, always. Strip out special case for "existing tags" profile, replace with an empty temp profile so all can be treated the same.

lib/state/upload_queue_state.dart

@@ -130,6 +130,7 @@ class UploadQueueState extends ChangeNotifier {
       profile: session.profile!,  // Safe to use ! because commitSession() checks for null
       operatorProfile: session.operatorProfile,
       refinedTags: session.refinedTags,
+      additionalExistingTags: session.additionalExistingTags, // Always empty for new nodes
       changesetComment: session.changesetComment,
       uploadMode: uploadMode,
       operation: UploadOperation.create,
@@ -188,6 +189,7 @@ class UploadQueueState extends ChangeNotifier {
       profile: session.profile!,  // Safe to use ! because commitEditSession() checks for null
       operatorProfile: session.operatorProfile,
       refinedTags: session.refinedTags,
+      additionalExistingTags: session.additionalExistingTags,
       changesetComment: session.changesetComment,
       uploadMode: uploadMode,
       operation: operation,