Enhance node processing and error handling in workflow mappers

- Improved reference handling in NodeMapper to support integer node IDs and added error logging for reference processing failures.
- Updated LoraLoaderMapper and LoraStackerMapper to handle lora_stack as a dictionary, ensuring compatibility with new data formats.
- Refactored trace_model_path utility to perform a depth-first search for LoRA nodes, improving the accuracy of model path tracing.
- Cleaned up unused code in parser.py related to LoRA processing, streamlining the workflow parsing logic.

simple_test.py

@@ -0,0 +1,25 @@
+import json
+from py.workflow.parser import WorkflowParser
+
+# Load workflow data
+with open('refs/prompt.json', 'r') as f:
+    workflow_data = json.load(f)
+
+# Parse workflow
+parser = WorkflowParser()
+try:
+    # Parse the workflow
+    result = parser.parse_workflow(workflow_data)
+    print("Parsing successful!")
+    
+    # Print each component separately
+    print("\nGeneration Parameters:")
+    for k, v in result.get("gen_params", {}).items():
+        print(f"  {k}: {v}")
+    
+    print("\nLoRAs:")
+    print(result.get("loras", ""))
+except Exception as e:
+    print(f"Error parsing workflow: {e}")
+    import traceback
+    traceback.print_exc()