create storybook folder outside of src and move "Guide" mdx stories

src/Umbraco.Web.UI.Client/.storybook/main.ts

@@ -1,7 +1,7 @@
 import { StorybookConfig } from '@storybook/web-components-vite';
 
 const config: StorybookConfig = {
-	stories: ['../@(src|libs|apps)/**/*.mdx', '../@(src|libs|apps)/**/*.stories.@(js|jsx|ts|tsx)'],
+	stories: ['../@(src|libs|apps|storybook)/**/*.mdx', '../@(src|libs|apps|storybook)/**/*.stories.@(js|jsx|ts|tsx)'],
 	addons: ['@storybook/addon-links', '@storybook/addon-essentials', '@storybook/addon-a11y'],
 	framework: {
 		name: '@storybook/web-components-vite',

src/Umbraco.Web.UI.Client/.storybook/preview.js

@@ -24,7 +24,7 @@ import { umbExtensionsRegistry } from '../libs/extensions-api';
 
 import '../src/core/context-provider/context-provider.element';
 import '../src/core/controller-host/controller-host-test.element';
-import '../src/backoffice/shared/components';
+import '../src/backoffice/core/components';
 
 import { manifests as documentManifests } from '../src/backoffice/documents';