CR 20260807 updates for Battles

CR 20260807 has been released: [source](https://media.wizards.com/2026/downloads/MagicCompRules%2020260807.txt)

I have a graphical diff between the previous rules and this revision available [here](https://muz.github.io/mtgrulediff/releases/20260619_to_20260807.html)

Aside from other items we've catered for in #14857 for Hone counters on Equipment, Storied, and Recruit; there are various updates to Battles that probably need some engine updates.

* Siege is not guaranteed to be the subtype on all Battles (310.12)
* Some "battles" rules are actually Siege specific (310.12)
* Having defense 0 on non-Siege battles sends it to the owner's graveyard (704.5w)
* Evasion abilities when defending a battle are explicitly called out and can be cumulative (509.1b)
* If a battle has no protector, and it's not being attacked, the battle's controller chooses a protector based on battle type. If there's no type, the controller must be chosen. (704.5x, 704.5y)
* May interact with scenarios involving player removal of the protector

Read the CR 20260807 source and the linked graphical diff first, then trace the engine's existing Battle handling against rules 310.12, 509.1b, 704.5w, 704.5x, and 704.5y. Done means the listed Siege subtype, defense-zero, evasion, and protector-selection behaviors are represented and covered by the relevant existing tests, if any.

Written by the indexing model from the issue text.