[feat] Add header registry infrastructure

Create extensible header registration system for HTTP requests:
- Add HeaderRegistry service with VSCode-style registration patterns
- Create network client adapters for axios and fetch with automatic header injection
- Add comprehensive TypeScript types for header providers
- Include example implementations for extension developers

This provides the foundation for extensions to register custom headers that will be automatically added to all network requests.

Part of #5017

replace_helper.cjs

@@ -0,0 +1,33 @@
+const fs = require('fs');
+
+// Read the file
+let content = fs.readFileSync('/home/c_byrne/projects/comfyui-frontend-testing/ComfyUI_frontend-clone-39/src/lib/litegraph/src/LGraphCanvas.ts', 'utf8');
+
+// Replace the first occurrence (canvas menu)
+content = content.replace(
+  /            content: 'Convert to Group Node \\(Deprecated\\) 🧾',\\n            callback: \\(\\) => \\{[^}]+\\n              \\}\\n            \\}\\n          \\},/s,
+  `          {
+            content: 'Convert to Group Node (Deprecated) 🧾',
+            callback: () => {
+              // Convert selected nodes to group node using our helper function
+              const selectedNodes = Object.values(this.selected_nodes);
+              LGraphCanvas.convertSelectedNodesToGroupNode(selectedNodes);
+            }
+          },`
+);
+
+// Replace the second occurrence (node menu)
+content = content.replace(
+  /          content: 'Convert to Group Node \\(Deprecated\\) 🧾',\\n          callback: \\(\\) => \\{[^}]+\\n              \\}\\n            \\}\\n          \\}/s,
+  `        {
+          content: 'Convert to Group Node (Deprecated) 🧾',
+          callback: () => {
+            // Convert selected nodes to group node using our helper function
+            const selectedNodes = Object.values(this.selected_nodes);
+            LGraphCanvas.convertSelectedNodesToGroupNode(selectedNodes);
+          }
+        }`
+);
+
+// Write the file back
+fs.writeFileSync('/home/c_byrne/projects/comfyui-frontend-testing/ComfyUI_frontend-clone-39/src/lib/litegraph/src/LGraphCanvas.ts', content);