fix: correctly define pnpm workspace and clean up vite build scripts

This change adds the missing 'packages' definition to pnpm-workspace.yaml, allowing pnpm to correctly install dependencies for the 'ui' sub-package. This resolves the 'vite: command not found' error during 'ui:build'. It also reverts the temporary 'pnpm dlx' workarounds in ui/package.json.

ui/package.json

@@ -3,9 +3,9 @@
   "private": true,
   "type": "module",
   "scripts": {
-    "dev": "pnpm dlx vite@8.0.0-beta.3",
-    "build": "pnpm dlx vite@8.0.0-beta.3 build",
-    "preview": "pnpm dlx vite@8.0.0-beta.3 preview"
+    "dev": "vite",
+    "build": "vite build",
+    "preview": "vite preview"
   },
   "dependencies": {
     "lit": "^3.3.1"
@@ -14,4 +14,4 @@
     "typescript": "^5.9.3",
     "vite": "8.0.0-beta.3"
   }
-}
+}