chore(pg-sveltekit): vite 7 -> 8, vite-plugin-svelte 6 -> 7

Drops vite-plugin-top-level-await: it required `rollup` at module load
and vite 8 swaps rollup for rolldown, so the plugin is unloadable there.
With `build.target: 'esnext'`, vite 8 / rolldown passes top-level await
through unchanged for modern browsers (Chrome 89+, Firefox 89+, Safari 15+),
which the wasm plugin's init relies on. Concurrent TLA imports become
sequential after bundling (rolldown semantics), so init may be marginally
slower but still correct.

- vite 7.3.2 -> 8.0.13
- @sveltejs/vite-plugin-svelte 6.2.4 -> 7.1.2
- remove vite-plugin-top-level-await

Author: rubenhensen