## What does this PR do?
- Adds a welcome modal for new Cal.com users
- Implements timezone display in the weekly calendar view
- Creates a hook for fetching onboarding calendar events
## Visual Demo (For contributors especially)
#### Image Demo:
## Mandatory Tasks
- [x] I have self-reviewed the code
- [x] I have updated the developer docs in /docs
- [x] I confirm automated tests are in place that prove my fix is effective or that my feature works.
## How should this be tested?
1. **Welcome Modal:**
- Create a new user account
- Verify the welcome modal appears with correct content
- Test the "Continue" button closes the modal
- Check that the modal can be triggered via URL parameter `?welcomeToCalcomModal=true`
2. **Timezone Display:**
- Go to the weekly calendar view
- Verify the timezone is displayed correctly when `showTimezone` is enabled
- Test with different timezones to ensure proper formatting
3. **Onboarding Calendar Events:**
- Test the hook by connecting a calendar during onboarding
- Verify events are fetched and displayed correctly
- Check that events refresh when new calendars are connected
## Checklist
- I have read the [contributing guide](https://github.com/calcom/cal.com/blob/main/CONTRIBUTING.md)
- My code follows the style guidelines of this project
- I have commented my code, particularly in hard-to-understand areas
- I have checked if my changes generate no new warnings
