fix(inkscape): use xvfb-run for headless execution

- Inkscape requires X11 display connection, causing 'GtkStyleContext without display' error
- Solution: use xvfb-run to create virtual X11 display
- Fallback: try direct inkscape if xvfb-run fails
- Add xvfb package to Dockerfile
- Update inkscape tests for new xvfb-run behavior

Fixes: Gtk-ERROR: Can't create a GtkStyleContext without a display connection

.github/workflows/release.yml

@@ -389,7 +389,7 @@ jobs:
           echo ""
           echo "📋 檢查關鍵轉檔工具..."
           TOOLS=("libreoffice --version" "pandoc --version" "ffmpeg -version" "tesseract --version" "pdf2zh --help" "mineru --help" "babeldoc --help")
-          
+
           for tool_cmd in "${TOOLS[@]}"; do
             TOOL_NAME=$(echo "$tool_cmd" | cut -d' ' -f1)
             echo -n "  ${TOOL_NAME}: "