feat: default to Getting Started category for new users in templates modal (#8599)

## Summary

Updates the templates modal to default to the "Getting Started" category
for new users.

## Changes

- Add `initialCategory` prop to `WorkflowTemplateSelectorDialog`
component
- Integrate `useNewUserService` in the dialog composable to detect
first-time users
- New users automatically see the "basics-getting-started" category
- Existing users continue to see "all" templates as default
- Allow explicit category override via options parameter

## Testing

- Added unit tests covering all scenarios (new user, non-new user,
undetermined, explicit override)
- 6 tests pass

Fixes COM-9146

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8599-feat-default-to-Getting-Started-category-for-new-users-in-templates-modal-2fd6d73d365081d4a5fad2abdb768269)
by [Unito](https://www.unito.io)

src/composables/useWorkflowTemplateSelectorDialog.ts

@@ -1,26 +1,37 @@
 import WorkflowTemplateSelectorDialog from '@/components/custom/widget/WorkflowTemplateSelectorDialog.vue'
 import { useTelemetry } from '@/platform/telemetry'
 import { useDialogService } from '@/services/dialogService'
+import { useNewUserService } from '@/services/useNewUserService'
 import { useDialogStore } from '@/stores/dialogStore'
 
 const DIALOG_KEY = 'global-workflow-template-selector'
+const GETTING_STARTED_CATEGORY_ID = 'basics-getting-started'
 
 export const useWorkflowTemplateSelectorDialog = () => {
   const dialogService = useDialogService()
   const dialogStore = useDialogStore()
+  const newUserService = useNewUserService()
 
   function hide() {
     dialogStore.closeDialog({ key: DIALOG_KEY })
   }
 
-  function show(source: 'sidebar' | 'menu' | 'command' = 'command') {
+  function show(
+    source: 'sidebar' | 'menu' | 'command' = 'command',
+    options?: { initialCategory?: string }
+  ) {
     useTelemetry()?.trackTemplateLibraryOpened({ source })
 
+    const initialCategory =
+      options?.initialCategory ??
+      (newUserService.isNewUser() ? GETTING_STARTED_CATEGORY_ID : 'all')
+
     dialogService.showLayoutDialog({
       key: DIALOG_KEY,
       component: WorkflowTemplateSelectorDialog,
       props: {
-        onClose: hide
+        onClose: hide,
+        initialCategory
       },
       dialogComponentProps: {
         pt: {