Both deal_damage and attack_damage now check if the target is knocked out
after applying damage. If KO'd, EffectResult includes:
- details['knockout'] = True
- details['knockout_pokemon_id'] = target's instance_id
- Message includes 'knocked out!' notification
Knockout check correctly respects HP modifiers via effective_hp().
Added 9 tests covering knockout detection, HP modifier behavior,
weakness-triggered knockouts, and resistance preventing knockouts.
1fbd3d1cfa