ci: free disk space on self-hosted runner before each job

Add a pre-checkout cleanup step that removes stale act caches,
old setup-node/npm cache entries, dangling docker resources, and
leftover /tmp files older than 2h. Prevents recurring ENOSPC
failures on the EC2 self-hosted runner.

Note: the very first run after this change may still fail if the
runner disk was already at 100% beforehand; one-time manual cleanup
on the host is required to bootstrap.

.gitea/workflows/deploy.yml

@@ -10,6 +10,36 @@ jobs:
     runs-on: self-hosted
 
     steps:
+      - name: Free disk space
+        run: |
+          set +e
+          echo "=== Disk before cleanup ==="
+          df -h
+          # Stale act runner workspaces from previous jobs (older than 60 min).
+          if [ -d "$HOME/.cache/act" ]; then
+            du -sh "$HOME/.cache/act" 2>/dev/null
+            find "$HOME/.cache/act" -mindepth 1 -maxdepth 1 -type d -mmin +60 -exec rm -rf {} + 2>/dev/null
+          fi
+          # Stale runner workspaces under common locations.
+          for dir in "$HOME/actions-runner/_work" "$HOME/.cache/setup-node" "$HOME/.npm/_cacache"; do
+            if [ -d "$dir" ]; then
+              find "$dir" -mindepth 1 -maxdepth 2 -mmin +1440 -exec rm -rf {} + 2>/dev/null
+            fi
+          done
+          # Docker leftovers if docker is available.
+          if command -v docker >/dev/null 2>&1; then
+            docker image prune -af --filter "until=24h" 2>/dev/null
+            docker container prune -f --filter "until=24h" 2>/dev/null
+            docker builder prune -af --filter "until=24h" 2>/dev/null
+          fi
+          # Stale /tmp files older than 2h, keep currently-running runner files.
+          find /tmp -mindepth 1 -maxdepth 1 -mmin +120 \
+            -not -name 'runner*' -not -name 'act*' \
+            -exec rm -rf {} + 2>/dev/null
+          echo "=== Disk after cleanup ==="
+          df -h
+          exit 0
+
       - name: Checkout code
         uses: actions/checkout@v4