Umbra Studio v0.22.6

Updater Recovery Hotfix

• Fixed the standalone updater remaining permanently stuck on Stopping Umbra Studio after an interrupted update, reboot, or updater crash.
• Added automatic recovery for abandoned active states so a dead update becomes
  a clear, retryable failure instead of disabling the updater indefinitely.
• Moved Umbra shutdown ownership into the detached external update worker. The
  update request and worker now exist before shutdown begins, closing the handoff
  gap that could leave no worker, request, or failure log behind.
• Added session heartbeats for the updater and worker so Windows PID reuse after
  a reboot cannot be mistaken for a still-running update.
• Added exact-process shutdown safeguards. A standalone updater refuses to
  replace application files when an unknown Umbra listener is still active.
• Reduced abandoned updater workspace retention to one minute while preserving
  any session with a live heartbeat, preventing old release archives and bundled
  runtimes from accumulating under User/Cache/UmbraUpdater.