A remote Orca server whose workspace window is closed keeps answering status RPC, so Settings > Available Hosts showed "Ready" and the status bar showed "Connected" while every graph-backed operation failed. Adds the shared predicate `isRuntimeWorkspaceWindowClosed` (`graphStatus !== 'ready' && desktopWindowStatus === 'openable'`) and one host-health derivation with a new `workspace-window-closed` state, consumed by both surfaces. Hosts that omit `desktopWindowStatus` are unaffected, so the connected-host count and overall dot do not regress.
Fixes#12350
Co-authored-by: gatsby74 <gatsby74@users.noreply.github.com>
