chore(app): scaffold tauri 2 + react + vite, window launches

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/index.html

@@ -0,0 +1,11 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <title>spacesh</title>
+  </head>
+  <body>
+    <div id="root"></div>
+    <script type="module" src="/src/main.tsx"></script>
+  </body>
+</html>