Umbra Studio v0.22.3

Updater Shutdown Hotfix

• Removed automatic Umbra Studio relaunching after both successful and failed
  update attempts. The updater now finishes independently and asks the user to
  start Umbra Studio manually.
• Removed the post-update health wait that could leave a blank launcher
  terminal, a hung Bun process, or an unavailable application port.
• Replaced the updater's Open Umbra action with a clean Close updater
  action that cannot interrupt an active installation.
• Added Windows and Linux package gates that reject updater bundles if an
  automatic relaunch path returns.