feat: scaffold Tauri v2 + React + TS with all dependencies

- Tauri v2 with React 19 + TypeScript + Vite 7
- Tauri plugins: fs, dialog, shell (registered in lib.rs)
- Filesystem permissions scoped to $APPDATA/openpylon/**
- Tailwind CSS v4 via @tailwindcss/vite
- shadcn/ui initialized with 12 components
- All app dependencies: Zustand, zundo, dnd-kit, Framer Motion,
  Zod, ulid, date-fns, react-markdown, remark-gfm
- Path alias @/* configured in tsconfig + vite

src-tauri/src/lib.rs

@@ -0,0 +1,10 @@
+#[cfg_attr(mobile, tauri::mobile_entry_point)]
+pub fn run() {
+    tauri::Builder::default()
+        .plugin(tauri_plugin_opener::init())
+        .plugin(tauri_plugin_fs::init())
+        .plugin(tauri_plugin_dialog::init())
+        .plugin(tauri_plugin_shell::init())
+        .run(tauri::generate_context!())
+        .expect("error while running tauri application");
+}