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/icons/android/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+  <foreground android:drawable="@mipmap/ic_launcher_foreground"/>
+  <background android:drawable="@color/ic_launcher_background"/>
+</adaptive-icon>