Add changeset for background command disconnect

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: mishushakov

.changeset/disconnect-after-run.md

@@ -0,0 +1,6 @@
+---
+"@e2b/desktop": patch
+"@e2b/desktop-python": patch
+---
+
+Disconnect from fire-and-forget background commands. After background `commands.run` calls whose output is never read (`xdg-open`, `gtk-launch`, `Xvfb`, `startxfce4`), the SDK now calls `.disconnect()` so it stops holding the command's event stream open while the process keeps running.