ci: bump Node to 22.21.1 to fix build (registerHooks requires >=22.15.0)

@cloudflare/vite-plugin 1.43.0 imports `registerHooks` from `node:module`,
which was added in Node 22.15.0. CI ran 22.14.0, causing the build to fail
with "does not provide an export named 'registerHooks'".

- .nvmrc: 22.14.0 -> 22.21.1
- ci.yml: read node-version-file (.nvmrc) so CI and local stay in sync
- package.json engines: >=22.14.0 -> >=22.15.0

Author: claudio-silva

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v6
         with:
-          node-version: "22.14.0"
+          node-version-file: ".nvmrc"
           cache: "npm"
 
       - name: Install dependencies

.nvmrc

@@ -1 +1 @@
-22.14.0
+22.21.1

package-lock.json

@@ -4,7 +4,7 @@
   "version": "1.0.0",
   "type": "module",
   "engines": {
-    "node": ">=22.14.0 <23"
+    "node": ">=22.15.0 <23"
   },
   "cloudflare": {
     "label": "Cloudflare Fullstack SaaS Starter",