feat: Tauri desktop app scaffold

- src-tauri/ with Rust backend, Cargo.toml, main.rs, lib.rs
- tauri.conf.json: Linux deb bundle with webkit2gtk deps
- package.json: added tauri script
- Build on a machine with Rust: cd web && npm run tauri build

web/src-tauri/build.rs

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