fix: support 1GB RAM VPS for Docker image builds

- workflow: limit Node.js to 768MB (NODE_OPTIONS --max-old-space-size)
  and remove GitHub Actions cache (not supported on Forgejo Actions)
- install: auto-create 2GB swapfile when installing Forgejo Runner so
  the build process does not OOM on low-RAM machines

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/docker-publish.yml

@@ -43,10 +43,10 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: 20
-          cache: 'yarn'
-          cache-dependency-path: frontend/yarn.lock
 
       - name: Install Frontend Dependencies & Build
+        env:
+          NODE_OPTIONS: "--max-old-space-size=768"
         run: |
           cd frontend
           yarn install --frozen-lockfile
@@ -80,5 +80,3 @@ jobs:
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
           platforms: linux/amd64
-          cache-from: type=gha
-          cache-to: type=gha,mode=max

install.sh

@@ -778,6 +778,19 @@ do_forgejo_runner_install() {
 
     mkdir -p "$FORGEJO_RUNNER_DIR"
 
+    # Ensure swap exists for low-RAM VPS (Docker image builds need ~2GB memory)
+    if [ ! -f /swapfile ]; then
+        log_step "Creating 2GB swapfile for build memory..."
+        fallocate -l 2G /swapfile
+        chmod 600 /swapfile
+        mkswap /swapfile > /dev/null
+        swapon /swapfile
+        echo '/swapfile none swap sw 0 0' >> /etc/fstab
+        log_ok "Swapfile created and enabled (persistent across reboots)."
+    else
+        log_ok "Swapfile already exists, skipping."
+    fi
+
     # gitea/act_runner auto-registers on first start via env vars, then starts daemon
     log_step "Starting Forgejo Runner (auto-register on first boot)..."
     docker run -d \