fix(ci): install node in container for actions/* post steps

Gitea Actions run actions as JavaScript via `node` inside the
job container. The maven:3.9.6-eclipse-temurin-21 image has no
node, so action post steps (e.g. Checkout cleanup) fail with
'exec: "node": executable file not found in $PATH'.

Extend the install step to add git AND node 22 via NodeSource
apt repo, so the runner can complete every action's pre/post step.

.gitea/workflows/ci.yml

@@ -20,11 +20,15 @@ jobs:
     container:
       image: maven:3.9.6-eclipse-temurin-21
     steps:
-      - name: Install git and basic tools
+      - name: Install git, node, and basic tools
         run: |
           apt-get update
-          apt-get install -y git ca-certificates
+          apt-get install -y git curl ca-certificates
+          curl -fsSL https://deb.nodesource.com/setup_22.x | bash -
+          apt-get install -y nodejs
           rm -rf /var/lib/apt/lists/*
+          git --version
+          node --version
 
       - name: Checkout
         uses: actions/checkout@v4