Normalize quickstart type comparison and improve port assignment logic

[ramya18101]

🔧 Changes

This PR refactors the quickstart setup command logic in internal/cli/quickstarts.go to improve type comparison consistency and port assignment flow.

📚 References

🔬 Testing

Manual Testing Steps:

• Run auth0 quickstarts setup --type vite - verify it accepts the type parameter
• Run auth0 quickstarts setup --type nextjs - verify it accepts the type parameter
• Run auth0 quickstarts setup and select "vite" - verify default port 5173 is offered
• Run auth0 quickstarts setup and select "nextjs" - verify default port 3000 is offered

📝 Checklist

• All new/changed/fixed functionality is covered by tests (or N/A)
• I have added documentation for all new/changed functionality (or N/A)