Clearer guidance for domain connection errors

We've improved the domain connection step in onboarding. When a domain is registered on one Hostinger account but you're trying to connect it to a website on a different account, you now see actionable guidance explaining what to do next. Previously, users saw only an error message and had to contact support or use the AI assistant for help. The resolution steps are now built directly into the interface, so you can self-serve without needing to reach out.