Add Node.js setup, dependency installation, and static export steps to Docker GHCR workflow

Author: joancipria

.github/workflows/docker-ghcr.yml

@@ -19,6 +19,24 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "20"
+          cache: "pnpm"
+
+      - name: Install dependencies
+        run: |
+          corepack enable pnpm
+          pnpm install --frozen-lockfile
+
+      - name: Build static export
+        env:
+          NEXT_PUBLIC_API_URL: ${{ vars.NEXT_PUBLIC_API_URL || '' }}
+        run: |
+          pnpm build
+          pnpm export
+
       - name: Extract metadata (tags, labels)
         id: meta
         uses: docker/metadata-action@v5