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/pages/CanvasView.tsx

@@ -472,7 +472,8 @@ export function CanvasView() {
         </div>
 
         {/* Config Panel - use V2 for spec mode, legacy for AtomizerCanvas */}
-        {selectedNodeId && !showChat && (
+        {/* Shows INSTEAD of chat when a node is selected */}
+        {selectedNodeId ? (
           useSpecMode ? (
             <NodeConfigPanelV2 onClose={() => useSpecStore.getState().clearSelection()} />
           ) : (
@@ -480,10 +481,7 @@ export function CanvasView() {
               <NodeConfigPanel nodeId={selectedNodeId} />
             </div>
           )
-        )}
-
-        {/* Chat/Assistant Panel */}
-        {showChat && (
+        ) : showChat ? (
           <div className="w-96 border-l border-dark-700 bg-dark-850 flex flex-col">
             {/* Chat Header */}
             <div className="flex items-center justify-between px-4 py-3 border-b border-dark-700">
@@ -524,7 +522,7 @@ export function CanvasView() {
               isConnected={isConnected}
             />
           </div>
-        )}
+        ) : null}
       </main>
 
       {/* Template Selector Modal */}