Install mono-devel in electron-build CI job

Squirrel maker needs Mono + Wine to create Windows installer on Linux.
Added diagnostic output for Wine/Mono versions.

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

.gitlab-ci.yml

@@ -78,10 +78,14 @@ electron-build:
     - if: $CI_COMMIT_BRANCH == "main"
       when: manual
       allow_failure: true
+  before_script:
+    - apt-get update && apt-get install -y --no-install-recommends mono-devel && rm -rf /var/lib/apt/lists/*
   script:
     - |
       VERSION=$(cat VERSION 2>/dev/null || echo "0.0.0")
       echo "[Electron] Building v${VERSION} for Windows..."
+      echo "[Electron] Wine: $(wine --version 2>/dev/null || echo 'not found')"
+      echo "[Electron] Mono: $(mono --version 2>/dev/null | head -1 || echo 'not found')"
 
       cd electron
       node -e "