This is a placeholder ICO file. To properly convert the SVG to ICO format, you'll need to:

1. Use an online converter like:
   - https://convertio.co/de/svg-ico/
   - https://cloudconvert.com/svg-to-ico
   
2. Or install ImageMagick and run:
   convert app-icon.svg -resize 256x256 app-icon.ico

3. Or use a tool like Inkscape to export as ICO

The SVG file (app-icon.svg) contains a blue square icon that you can convert.