Fix directory structure

[davidstanke]

The directory structure is dorky: svelte and svelte_v4.BAK -- which is vestigial. Let's move the contents of svelte to the root, delete svelte_v4.BAK, and update netlify.toml accordingly.

(NB: I was having some trouble with the netlify config -- it's unclear whether it's drawing from the toml file or from config in the netlify UI; we may need to fiddle with that)