Fix UnprocessableEntityError import issue

- Remove UnprocessableEntityError import that doesn't exist in clerk-backend-api
- This was causing Clerk SDK to appear unavailable in HTTP adapter
- Keep only Clerk import which is sufficient for our needs

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

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

mcp_auth_http_adapter.py

@@ -17,16 +17,10 @@ from fastapi.responses import RedirectResponse, JSONResponse
 # Try to import Clerk SDK
 try:
     from clerk_backend_api import Clerk
-    from clerk_backend_api.types import UnprocessableEntityError
     CLERK_AVAILABLE = True
-    print(f"DEBUG: Clerk SDK imported successfully in HTTP adapter")
 except ImportError as e:
     CLERK_AVAILABLE = False
     Clerk = None
-    UnprocessableEntityError = None
-    print(f"DEBUG: Clerk SDK import failed in HTTP adapter: {e}")
-
-print(f"DEBUG: CLERK_AVAILABLE in HTTP adapter = {CLERK_AVAILABLE}")
 
 logger = logging.getLogger(__name__)