fix(web): upgrade vite and restore devfront build

- switch adminfront and devfront to vite 8
- fix devfront TypeScript baseline build errors
- require Node.js 24 LTS or newer in package metadata and docs

Co-Authored-By: First Fluke <our.first.fluke@gmail.com>

userfront-e2e/package.json

@@ -3,6 +3,9 @@
   "version": "0.1.0",
   "private": true,
   "type": "module",
+  "engines": {
+    "node": ">=24.0.0"
+  },
   "scripts": {
     "test": "playwright test",
     "test:ui": "playwright test --ui",