fix: remove problematic empty environment variables for Windows build

- Remove WIN_CSC_LINK and WIN_CSC_KEY_PASSWORD empty string env vars
- These were causing electron-builder to fail with 'not a file' error
- Keep CSC_IDENTITY_AUTO_DISCOVERY=false to disable code signing

Author: rui-typelets

.github/workflows/desktop-build.yml

@@ -53,8 +53,6 @@ jobs:
         run: cd apps/desktop && npm run build:${{ matrix.platform }}
         env:
           CSC_IDENTITY_AUTO_DISCOVERY: false
-          WIN_CSC_LINK: ""
-          WIN_CSC_KEY_PASSWORD: ""
 
       - name: List built files
         run: |