Delete Printer: a queue that's already gone is a successful delete

Judge the delete by the read-back (is the queue gone?) instead of lpadmin's exit
status. Deleting a queue that was removed elsewhere before the sidebar refreshed
made lpadmin fail with 'The printer or class does not exist', and the app showed a
failure alert although the queue was gone. Now the status bar shows 'Deleted <queue>'
and os_log notes it was already deleted. Unit tests for all four outcomes, plus an
opt-in live test (CUPSKIT_LIVE_DELETE=1) on a name that never existed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Sources/CUPSAdminApp/PrinterStore.swift

@@ -251,7 +251,7 @@ final class PrinterStore {
             deleted = outcome.succeeded
             if deleted {
                 report("Deleted \(queue) in \(elapsedText(since: started))")
-                log.info("deleted \(queue, privacy: .public)")
+                log.info("deleted \(queue, privacy: .public)\(outcome.message.map { " (\($0))" } ?? "", privacy: .public)")
             } else {
                 report("ERROR: delete \(queue): \(outcome.message ?? "failed")")
                 fail("Couldn’t delete \(queue)", "\(outcome.message ?? "failed")\n\n\(outcome.command)")