Photon 2.0.0 betas are out

The Svelte 5 migration has progressed enough that I think it's safe to release betas now.

Docker tags are released for 2.0.0-beta.2, and you can access the latest beta yourself at https://svelte-5.photon-8na.pages.dev/.

I've made a few UX changes to match the new codebase, I hope that this release is good for you.

Please let me know of any major issues.