ci: build on Node 22 and 24, the versions Astro 6 actually runs on

The matrix still tested Node 20, inherited from when this branch carried
the AstroWind landing on Astro 5. Astro 6 refuses to start below 22.12.0,
so the Node 20 leg failed on `astro build` and cancelled the Node 22 leg
with it.

package.json claimed engines >=20.0.0 for the same reason. Now it says
what the toolchain needs, so a wrong local Node fails at install with a
clear message instead of halfway through a build.

Author: begeistert

.github/workflows/actions.yaml

@@ -28,9 +28,10 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
+        # Astro 6 requires >=22.12.0, so Node 20 cannot build this site at all.
         node-version:
-          - 20
           - 22
+          - 24
     steps:
       - uses: actions/checkout@v4
       - name: Use Node.js v${{ matrix.node-version }}

package.json

@@ -4,7 +4,7 @@
   "description": "PyMCU Landing Page - Modern web application for PyMCU project built with Astro, Tailwind CSS, Supabase, and AWS SES.",
   "type": "module",
   "engines": {
-    "node": ">=20.0.0"
+    "node": ">=22.12.0"
   },
   "scripts": {
     "dev": "astro dev",