feat(tree): add flat and lazy modes for tree data handling

* Implement flat mode to transform flat data with parentId to nested structure.
* Introduce lazy mode for on-demand loading of children.
* Update tree rendering logic to accommodate new modes.
* Enhance tree cell expansion logic to support lazy loading.
* Add dark mode styles for improved UI experience.
* Create comprehensive end-to-end tests for tree functionality.

.storybook/previewDecorator.tsx

@@ -8,7 +8,8 @@ import { ModalsProvider } from '@mantine/modals';
 import { GlobalStateStoreProvider } from '../src/GlobalStateStore';
 
 export const PreviewDecorator: Decorator = (Story, context) => {
-  const { parameters } = context;
+  const { parameters, globals } = context;
+  const colorScheme = globals.colorScheme as 'light' | 'dark';
 
   // Allow stories to opt-out of GlobalStateStore provider
   const useGlobalStore = parameters.globalStore !== false;
@@ -21,7 +22,7 @@ export const PreviewDecorator: Decorator = (Story, context) => {
   };
 
   return (
-    <MantineProvider>
+    <MantineProvider forceColorScheme={colorScheme}>
       
       <ModalsProvider>
         {useGlobalStore ? (