fix(demo): set github pages base path

Author: dvcorreia

.github/workflows/pages.yml

@@ -1,6 +1,7 @@
 name: Deploy demo to GitHub Pages
 
 on:
+  workflow_dispatch:
   push:
     tags:
       - "v*"

demo/package.json

@@ -4,7 +4,7 @@
   "version": "0.0.0",
   "type": "module",
   "scripts": {
-    "build": "tsc && vite build",
+    "build": "tsc && vite build --base=/nix-eval/",
     "dev": "vite",
     "test:node:cjs": "node test/node-cjs.cjs",
     "test:node:esm": "node test/node-esm.mjs"