Add library grid for games and Steam

Replace the profile-heavy sidebar with a Games & Apps library grid and move Add Game into the toolbar and library surface.

Add Steam as a protected library app while keeping it available as a dependency for other profiles, and detect Steam appmanifest entries as Steam-backed game tiles launched through AppID commands.

Bump the app version to 0.1.5 and update GUI documentation.

Author: MoonTheRipper