Wave of Rats does not return to the battlefield on death despite having dealt damage to a player

[[Wave of Rats]] reads:

> When Wave of Rats dies, if it dealt combat damage to a player this turn, return it to the battlefield under its owner’s control.

Currently, when Wave of Rats dies (having dealt damage to a player that turn), nothing exceptional happens.

Locate the Wave of Rats card implementation and use its death-handling behavior as the entry point. Check how combat damage and return-to-battlefield effects are represented for comparable cards, then verify that the card returns after dying following combat damage to a player.

Written by the indexing model from the issue text.