Default to the local registry in the UI

[filmor]

Change the UI default to the locally hosted registry.

Motivation and Context

Was quite confusing at first :)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

[domdomegg]

I think it would probably be best to default to the registry that you're currently looking at.

E.g. if you're on prod, show prod. If you're at localhost show local. (and same for staging)