fix: use electron-builder Wine image, disable code signing

- Runner now uses electronuserland/builder:20-wine which has Node 20,
  Wine, and all build tools pre-installed
- Removed manual Wine/Node setup steps from workflow
- Disabled Windows code signing (no certificate available)
- Simplified workflow to: checkout -> npm ci -> build -> package -> release

.gitea/workflows/release.yml

@@ -13,32 +13,20 @@ jobs:
         with:
           submodules: true
 
-      - uses: actions/setup-node@v4
-        with:
-          node-version: "20"
-          cache: "npm"
-
       - name: Install dependencies
         run: npm ci
 
       - name: Build backend + frontend + electron
         run: npm run build:all
 
-      - name: Install system dependencies
-        run: |
-          dpkg --add-architecture i386
-          apt-get update
-          apt-get install -y --no-install-recommends wine64 wine32 fakeroot rpm
-
       - name: Build Linux AppImage
         run: npx electron-builder --linux --publish never
 
       - name: Build Windows Installer
+        run: npx electron-builder --win --publish never
         env:
-          WINEDEBUG: "-all"
-        run: |
-          wine64 --version || wine --version || echo "wine check"
-          npx electron-builder --win --publish never
+          WIN_CSC_LINK: ""
+          WIN_CSC_KEY_PASSWORD: ""
 
       - name: Create Gitea Release and upload assets
         run: |