macOS DetailedList: Use swipe-to-reveal actions a la iOS

### Describe the bug

On macOS DetailedList, swiping on the item does not reveal any actions. This is native; see https://developer.apple.com/documentation/appkit/nstableviewdelegate/tableview(_:rowactionsforrow:edge:)?language=objc

### How to reproduce the bug

Run DetailedList demo; swipe on item with trackpad; nothing happens

### Minimum example code

```shell

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### Screenshots

_No response_

### Environment details

macOS 26.3, latest released Toga

### Logs

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### Additional context

We should still keep the context menu, as the native behavior in Mail still shows the actions in context menu.

Run the DetailedList demo and reproduce the missing swipe action with a macOS trackpad. Start by locating the macOS DetailedList implementation and compare its table view delegate behavior with Apple's rowActionsForRow API. Done means swiping reveals actions while the existing context menu remains available.

Written by the indexing model from the issue text.