chore: scaffold Tauri 2 + Svelte 5 workspace

Standard Tauri layout with a Svelte 5 + TypeScript + Vite frontend and a
Rust backend in src-tauri. Adds build tooling, app/window config,
capabilities, generated icons and the project README.

src-tauri/build.rs

@@ -0,0 +1,3 @@
+fn main() {
+    tauri_build::build()
+}