feat: add email verification check for cloud onboarding (#5636)

## Summary
- Added email verification flow for new users during onboarding
- Implemented invite code claiming with proper validation 
- Updated API endpoints from `/invite/` to `/invite_code/` for
consistency

## Changes

### Email Verification
- Added `CloudVerifyEmailView` component with email verification UI
- Added email verification check after login in `CloudLoginView`
- Added `isEmailVerified` property to Firebase auth store
- Users must verify email before claiming invite codes

### Invite Code Flow
- Enhanced `CloudClaimInviteView` with full claim invite functionality
- Updated `InviteCheckView` to route users based on email verification
status
- Modified API to return both `claimed` and `expired` status for invite
codes
- Added proper error handling and Sentry logging for invite operations

### API Updates
- Changed endpoint paths from `/invite/` to `/invite_code/` 
- Updated `getInviteCodeStatus()` to return `{ claimed: boolean;
expired: boolean }`
- Updated `claimInvite()` to return `{ success: boolean; message: string
}`

### UI/UX Improvements
- Added Korean translations for all new strings
- Improved button styling and layout in survey and waitlist views
- Added proper loading states and error handling

## Test Plan
- [ ] Test new user signup flow with email verification
- [ ] Test invite code validation (expired/claimed/valid codes)
- [ ] Test email verification redirect flow
- [ ] Test invite claiming after email verification
- [ ] Verify Korean translations display correctly

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

---------

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

src/platform/onboarding/cloud/UserCheckView.vue

@@ -17,7 +17,7 @@
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-  <div v-else class="flex items-center justify-center min-h-screen">
+  <div v-else class="flex items-center justify-center">
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 </template>