fix(canvas): Bug fixes for node movement, drag-drop, config panel, and introspection

- SpecRenderer: Add localNodes state with applyNodeChanges for smooth node dragging
- SpecRenderer: Fix getDefaultNodeData() - extractor uses 'custom_function' type with function definition
- SpecRenderer: Fix constraint default - use constraint_type instead of type
- CanvasView: Show config panel INSTEAD of chat when node selected (not blocked)
- NodeConfigPanelV2: Enable showHeader for code editor toolbar (Generate/Snippets/Validate/Test buttons)
- NodeConfigPanelV2: Pass studyId to IntrospectionPanel
- IntrospectionPanel: Accept studyId prop and use correct API endpoint
- optimization.py: Search multiple directories for model files including 1_setup/model/

atomizer-dashboard/frontend/src/components/canvas/panels/NodeConfigPanelV2.tsx

@@ -254,6 +254,7 @@ export function NodeConfigPanelV2({ onClose }: NodeConfigPanelV2Props) {
         <div className="fixed top-20 right-96 z-40">
           <IntrospectionPanel
             filePath={spec.model.sim.path}
+            studyId={useSpecStore.getState().studyId || undefined}
             onClose={() => setShowIntrospection(false)}
           />
         </div>
@@ -313,6 +314,7 @@ function ModelNodeConfig({ spec }: SpecConfigProps) {
         <div className="fixed top-20 right-96 z-40">
           <IntrospectionPanel
             filePath={spec.model.sim.path}
+            studyId={useSpecStore.getState().studyId || undefined}
             onClose={() => setShowIntrospection(false)}
           />
         </div>
@@ -694,38 +696,21 @@ function ExtractorNodeConfig({ node, onChange }: ExtractorNodeConfigProps) {
       {showCodeEditor && (
         <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/60 backdrop-blur-sm">
           <div className="w-[900px] h-[700px] bg-dark-850 rounded-xl overflow-hidden shadow-2xl border border-dark-600 flex flex-col">
-            {/* Modal Header */}
-            <div className="flex items-center justify-between px-4 py-3 border-b border-dark-700 bg-dark-900">
-              <div className="flex items-center gap-3">
-                <FileCode size={18} className="text-violet-400" />
-                <span className="font-medium text-white">Custom Extractor: {node.name}</span>
-                <span className="text-xs text-dark-500 bg-dark-800 px-2 py-0.5 rounded">.py</span>
-              </div>
-              <button
-                onClick={() => setShowCodeEditor(false)}
-                className="p-1.5 rounded hover:bg-dark-700 text-dark-400 hover:text-white transition-colors"
-              >
-                <X size={18} />
-              </button>
-            </div>
-            
-            {/* Code Editor */}
-            <div className="flex-1">
-              <CodeEditorPanel
-                initialCode={currentCode}
-                extractorName={node.name}
-                outputs={node.outputs?.map(o => o.name) || []}
-                onChange={handleCodeChange}
-                onRequestGeneration={handleRequestGeneration}
-                onRequestStreamingGeneration={handleStreamingGeneration}
-                onRun={handleValidateCode}
-                onTest={handleTestCode}
-                onClose={() => setShowCodeEditor(false)}
-                showHeader={false}
-                height="100%"
-                studyId={studyId || undefined}
-              />
-            </div>
+            {/* Code Editor with built-in header containing toolbar buttons */}
+            <CodeEditorPanel
+              initialCode={currentCode}
+              extractorName={`Custom Extractor: ${node.name}`}
+              outputs={node.outputs?.map(o => o.name) || []}
+              onChange={handleCodeChange}
+              onRequestGeneration={handleRequestGeneration}
+              onRequestStreamingGeneration={handleStreamingGeneration}
+              onRun={handleValidateCode}
+              onTest={handleTestCode}
+              onClose={() => setShowCodeEditor(false)}
+              showHeader={true}
+              height="100%"
+              studyId={studyId || undefined}
+            />
           </div>
         </div>
       )}