- Run Plugin Manager release fetches on OS threads so they execute in
parallel instead of serialising on the async executor.
- Reduce V4Connection shutdown poll from 3s to 100ms; the runner is killed
and reaped without blocking host shutdown.
- Add PluginManager::remove and PluginProcess::shutdown_and_wait so
uninstall can stop the runner before deleting files, fixing Windows
access-denied errors on plugin removal.
- Rebuild ribbon immediately after uninstall so the tab disappears.
83d7a4d7db