Fix attention_outputs error and alpha parameter issues

1. Fix 'attention_outputs' not defined error:
   - Change 'return attention_outputs' to 'return self.attention_outputs'
   - This fixes the NameError in ConceptAttention extraction

2. Fix alpha parameter validation issues:
   - Move alpha from 'required' to 'optional' in ConceptAttentionVisualizerNode
   - Remove alpha input from workflow JSON since it's now optional with default value
   - This resolves the 'Required input is missing: alpha' validation error

These changes ensure the workflow runs without validation errors while maintaining
the default alpha value of 0.5 for overlay blending.

concept_attention.py

@@ -52,7 +52,7 @@ class ConceptAttention:
             logger.warning("Could not access named_modules, using fallback method")
             self._register_hooks_fallback(actual_model, hook_fn)
         
-        return attention_outputs
+        return self.attention_outputs
     
     def _register_hooks_fallback(self, model, hook_fn):
         """

example_workflow.json

@@ -101,14 +101,13 @@
       "mode": 0,
       "inputs": [
         {"name": "concept_maps", "type": "CONCEPT_MAPS", "link": 4},
-        {"name": "image", "type": "IMAGE", "link": 1},
-        {"name": "alpha", "type": "FLOAT", "link": null}
+        {"name": "image", "type": "IMAGE", "link": 1}
       ],
       "outputs": [
         {"name": "visualized_image", "type": "IMAGE", "links": [11], "slot_index": 0}
       ],
       "properties": {"Node name for S&R": "ConceptAttentionVisualizerNode"},
-      "widgets_values": [0.5]
+      "widgets_values": []
     },
     {
       "id": 7,

nodes.py

@@ -686,6 +686,8 @@ class ConceptAttentionVisualizerNode:
             "required": {
                 "concept_maps": ("CONCEPT_MAPS",),
                 "image": ("IMAGE",),
+            },
+            "optional": {
                 "alpha": ("FLOAT", {
                     "default": 0.5,
                     "min": 0.0,