Detach closed Transfers window from shared transfer listeners

[Copilot]

Closing the Transfers window on macOS could leave behind transparent window instances that still intercepted clicks. The leak was specific to the transfer window lifecycle: closed controllers remained subscribed to the shared transfer collection and continued to receive updates after teardown.

• Transfer window lifecycle

  • keep TransferController collection listeners as fields instead of anonymous one-offs
  • unregister both the persistent reload listener and the temporary "collection loaded" listener during invalidate()
  • only register the temporary load listener while the collection is actually loading

• Transfer row controller cleanup

  • give TransferTableDataSource an explicit collection listener lifecycle
  • unregister its transfer-removed listener during invalidate()
  • invalidate and clear cached ProgressController instances on teardown so closed windows no longer retain row controllers

• Regression coverage

  • add a focused test that verifies TransferController and TransferTableDataSource remove their TransferCollection listeners when invalidated

@Override
public void invalidate() {
    collection.removeListener(collectionLoadedListener);
    collection.removeListener(collectionListener);
    transferTableModel.invalidate();
    super.invalidate();
}

• Fixes Invisible transfer windows remain on macOS after closing the Transfer window #18289

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