feat: scaffold Tauri + Svelte client

SvelteKit in SPA mode with Tauri v2. Builds and produces .deb bundle.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/src/routes/+layout.ts

@@ -0,0 +1,5 @@
+// Tauri doesn't have a Node.js server to do proper SSR
+// so we use adapter-static with a fallback to index.html to put the site in SPA mode
+// See: https://svelte.dev/docs/kit/single-page-apps
+// See: https://v2.tauri.app/start/frontend/sveltekit/ for more info
+export const ssr = false;