Update flatpak.xsh

Author: anki-code

flatpak.xsh

@@ -1,12 +1,10 @@
 """Flatpak xonshrc: sets up host command forwarding via flatpak-spawn."""
-import os
 
 # Add host-spawn symlinks directory to PATH (at the end, so sandbox commands take priority)
-_host_cmds = "/app/libexec/host-cmds"
-if os.path.isdir(_host_cmds):
-    $PATH.append(_host_cmds)
+with @.env.swap(HOST_CMDS="/app/libexec/host-cmds"):
+    if @.imp.os.path.isdir($HOST_CMDS):
+        $PATH.append($HOST_CMDS)
 
 # Convenience alias: run any command on the host explicitly
 aliases["host"] = lambda args: ![flatpak-spawn --host @(args)]
 
-del _host_cmds