feat: Phase 1 - Canvas with React Flow

- 8 node types (Model, Solver, DesignVar, Extractor, Objective, Constraint, Algorithm, Surrogate)
- Drag-drop from palette to canvas
- Node configuration panels
- Graph validation with error/warning display
- Intent JSON serialization
- Zustand state management

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

atomizer-dashboard/frontend/src/pages/CanvasView.tsx

@@ -0,0 +1,21 @@
+import { AtomizerCanvas } from '../components/canvas/AtomizerCanvas';
+
+export function CanvasView() {
+  return (
+    <div className="h-screen flex flex-col">
+      <header className="bg-white border-b border-gray-200 px-6 py-4">
+        <h1 className="text-xl font-bold text-gray-800">
+          Optimization Canvas
+        </h1>
+        <p className="text-sm text-gray-500">
+          Drag components from the palette to build your optimization workflow
+        </p>
+      </header>
+      <main className="flex-1 overflow-hidden">
+        <AtomizerCanvas />
+      </main>
+    </div>
+  );
+}
+
+export default CanvasView;