Describe the problem

Svelte 4 had foreign namespace to support Svelte Native. This was removed in Svelte 5 as the approach was not compatible with the new compiler implementation: #12709

Describe the proposed solution

Add a custom renderer API to support things like:

• Svelte Native: RFC: support for svelte 5 halfnelson/svelte-native#359
• Lynx: [Feature]: svelte guide lynx-family/lynx#144

Importance

nice to have