feat: Implement visual experiment designer and enhance landing page

- Add drag-and-drop experiment design capabilities using @dnd-kit libraries
- Introduce new experiment-related database schema and API routes
- Enhance landing page with modern design, gradients, and improved call-to-action sections
- Update app sidebar to include experiments navigation
- Add new dependencies for experiment design and visualization (reactflow, react-zoom-pan-pinch)
- Modify study and experiment schemas to support more flexible experiment configuration
- Implement initial experiment creation and management infrastructure

package.json

@@ -27,6 +27,9 @@
     "@aws-sdk/client-s3": "^3.735.0",
     "@aws-sdk/lib-storage": "^3.735.0",
     "@aws-sdk/s3-request-presigner": "^3.735.0",
+    "@dnd-kit/core": "^6.3.1",
+    "@dnd-kit/modifiers": "^9.0.0",
+    "@dnd-kit/sortable": "^10.0.0",
     "@hookform/resolvers": "^3.10.0",
     "@radix-ui/react-alert-dialog": "^1.1.6",
     "@radix-ui/react-avatar": "^1.1.2",
@@ -35,6 +38,7 @@
     "@radix-ui/react-dropdown-menu": "^2.1.5",
     "@radix-ui/react-label": "^2.1.1",
     "@radix-ui/react-popover": "^1.1.5",
+    "@radix-ui/react-scroll-area": "^1.2.3",
     "@radix-ui/react-select": "^2.1.5",
     "@radix-ui/react-separator": "^1.1.1",
     "@radix-ui/react-slider": "^1.2.2",
@@ -65,6 +69,8 @@
     "react-dom": "^18.3.1",
     "react-easy-crop": "^5.2.0",
     "react-hook-form": "^7.54.2",
+    "react-zoom-pan-pinch": "^3.7.0",
+    "reactflow": "^11.11.4",
     "server-only": "^0.0.1",
     "sonner": "^1.7.2",
     "superjson": "^2.2.1",