feat(gui): make desktop setup flow real and testable

Add a GUI-first setup gate and runtime state API so desktop onboarding is safe, iterative, and works with isolated fresh-mode installs. Scaffold and wire the desktop shell/runtime pieces so this branch runs end-to-end without disturbing existing user installs.

apps/gui/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "@hermes/gui",
+  "version": "0.0.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "node scripts/dev-shell.mjs",
+    "dev:tauri": "node scripts/tauri.mjs dev",
+    "build": "node scripts/tauri.mjs build",
+    "dashboard": "node scripts/start-dashboard.mjs",
+    "tauri": "node scripts/tauri.mjs"
+  }
+}