v1.5.1

Fixed

• External-game shortcuts now actually launch from Steam. Since v1.4.4
  every Heroic / Lutris / Flatpak / itch shortcut SLM added to Steam was
  broken: the URI or flatpak run ... command was written into Steam's
  exe field, which Steam treats as a file path. Clicking Play silently
  did nothing or, with Heroic in particular, crashed Steam outright when
  the overlay tried to attach to Electron.

  The launch command is now split into exe + launch_options, with
  three additional protections applied to every external launch:

  1. URIs are routed through their native launcher binary
     (/usr/bin/heroic, /usr/bin/lutris) so the dbus-bound xdg-open
     hop isn't needed - xdg-open is unreliable inside Steam's runtime.
  2. The whole invocation is wrapped in setsid -f so the launcher
     detaches into its own session and Steam stops tracking it
     immediately - no more "Anhalten" hangs, no more crashes when Steam
     waits forever for an Electron app to exit.
  3. env -u LD_PRELOAD -u LD_LIBRARY_PATH -u SteamAppId ... strips
     Steam's overlay shim and bookkeeping vars from the environment so
     Heroic / Proton / Wine start clean. Without this the Steam
     overlay's 32-bit shim leaks into 64-bit Wine processes and the
     game silently fails to launch.

  After updating, existing broken shortcuts in shortcuts.vdf need to
  be removed and re-added via the External Games dialog for the fix
  to take effect.