Fix issues with the Steam flatpak runner

lmm/cli.py

@@ -62,9 +62,8 @@ def launch(game: str, profile: str):
 
     # Launch the game
     if mounts_ok:
-        # runner.run()
-        # game.wait()
-        print(f"Stub runner: Would use {runner.__class__.__name__}")
+        runner.run(game)
+        game.wait()
 
     # Unmount
     for mount in mounts:

lmm/runners/steam.py

@@ -1,8 +1,9 @@
 import abc
 from pathlib import Path
 
+from lmm.cmd import run_cmd_nonblocking
 from lmm.runners.runner import Runner
-from lmm.games.game import Game
+from lmm.games.game import Game, ProtonGame
 
 
 class SteamRuntime(abc.ABC):