Remove unused JSON loading and serialization methods from PromptBuilder

lib/src/prompt_builder.dart

@@ -1,8 +1,7 @@
 class PromptBuilder {
   final String clientId;
   final Map<String, dynamic> _nodes = {};
-  final Map<String, Map<String, String>> _outputToNode =
+  final Map<String, Map<String, String>> _outputToNode = {};
-      {}; // Maps output tags to node IDs
   int _nodeIdCounter = 1;
 
   PromptBuilder({required this.clientId});
@@ -391,37 +390,4 @@ class PromptBuilder {
         return [];
     }
   }
-
-  /// Loads nodes from a JSON map
-  void loadFromJson(Map<String, dynamic> json) {
-    _nodes.clear();
-    _outputToNode.clear();
-
-    json.forEach((nodeId, nodeData) {
-      _nodes[nodeId] = nodeData;
-
-      // Register outputs of this node
-      final classType = nodeData["class_type"];
-      final defaultOutputs = _getDefaultOutputs(classType);
-      for (var i = 0; i < defaultOutputs.length; i++) {
-        final outputTag = nodeData["_meta"]?["outputTags"]
-                ?[defaultOutputs[i]] ??
-            defaultOutputs[i];
-        _outputToNode[outputTag] = {
-          "nodeId": nodeId,
-          "outputIndex": i.toString()
-        };
-      }
-    });
-
-    // Update the node ID counter to avoid collisions
-    _nodeIdCounter =
-        _nodes.keys.map(int.parse).fold(0, (max, id) => id > max ? id : max) +
-            1;
-  }
-
-  /// Converts the current nodes to a JSON map
-  Map<String, dynamic> toJson() {
-    return Map<String, dynamic>.from(_nodes);
-  }
 }