Code Review Bench PR #26775 - fix(companion): event type links for org user

[tomerqodo]

Code Review Bench PR calcom#26775

Original PR Title: fix(companion): event type links for org user
Original PR Description: ## What does this PR do?

Switch event type links to use the API-provided bookingUrl across the app and extension. This fixes broken links for org users and makes preview, share, and copy actions reliable.

Bug Fixes

• Use eventType.bookingUrl for preview/share/copy in Event Types screens and Event Type Detail, with clear error handling if missing
• List items now display URLs derived from bookingUrl via getDisplayUrl() helper
• Browser extension (content + LinkedIn) now uses bookingUrl with a fallback to username/slug
• Removed buildEventTypeLink from the service and added bookingUrl to the EventType type

UI

• Standardized action colors to black (#000000) and improved alignment/centering in headers, menus, buttons, and switches
• Minor iOS tweaks: adjusted create button layout and removed profile header borders

Updates since last revision

• Restored username fetching logic in event-type-detail.tsx to fix URL fallback display in BasicsTab when bookingUrl is unavailable (addresses Cubic AI review feedback, confidence 9/10)

Mandatory Tasks (DO NOT REMOVE)

• I have self-reviewed the code (A decent size PR without self-review might be rejected).
• I have updated the developer docs in /docs if this PR makes changes that would require a documentation change. N/A - no docs changes needed.
• I confirm automated tests are in place that prove my fix is effective or that my feature works.

How should this be tested?

1. Event Type Detail screen: Open an existing event type and verify the URL prefix shows correctly in the Basics tab
2. Preview/Copy/Share: Test these actions on event types - they should use the bookingUrl from the API
3. New event types: For unsaved event types, the URL fallback should show the actual username (not "username")
4. Browser extension: Test link insertion and copy on LinkedIn - should use bookingUrl with fallback

Human Review Checklist

• Verify username fetching works correctly in event-type-detail.tsx (the getUsername function was removed from CalComAPIService - confirm the restored useEffect uses the correct API)
• Test URL display in BasicsTab when bookingUrl is unavailable
• Test preview/share/copy across iOS and Android

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Link to Devin run: https://app.devin.ai/sessions/8627b1eb7efb4338aedc51929edec460
Requested by: Dhairyashil
Original PR URL: calcom#26775