[feat] Add skeleton loading states to cloud onboarding flow (#5568)

* [feat] Add skeleton loading states to cloud onboarding flow

- Create dedicated skeleton components matching exact layouts
- CloudLoginViewSkeleton for login page with beta notice, form, social buttons
- CloudSurveyViewSkeleton for multi-step survey with progress bar
- CloudWaitlistViewSkeleton for waitlist page with title and messages
- CloudClaimInviteViewSkeleton for invite claiming page
- Update UserCheckView to show contextual skeleton based on redirect destination
- Update InviteCheckView to show appropriate skeleton during loading
- Use i18n for loading text to maintain consistency

🤖 Generated with [Claude Code](https://claude.ai/code)

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

* [feat] Fix skeleton loading flow to show progressive states

- Start with simple loading text when checking user status
- Show survey skeleton while checking survey completion
- Show waitlist skeleton while checking user activation status
- Show login skeleton when redirecting to login on error
- Preserve all original comments from upstream authors
- Use progressive disclosure based on API response flow

🤖 Generated with [Claude Code](https://claude.ai/code)

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

---------

Co-authored-by: Claude <noreply@anthropic.com>

src/platform/onboarding/cloud/InviteCheckView.vue

@@ -1,5 +1,5 @@
 <template>
-  <div />
+  <CloudClaimInviteViewSkeleton />
 </template>
 
 <script setup lang="ts">
@@ -8,6 +8,8 @@ import { useRoute, useRouter } from 'vue-router'
 
 import { getInviteCodeStatus } from '@/api/auth'
 
+import CloudClaimInviteViewSkeleton from './skeletons/CloudClaimInviteViewSkeleton.vue'
+
 const router = useRouter()
 const route = useRoute()