Add background etc to stationed pokemon

[Mygod]

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[Mygod]

Other spots still read PokemonDisplay without ever touching LocationCard/background:

• decoder/pokemon.go:570,625,658,1199,1230 – all wild/map/nearby/encounter flows via setPokemonDisplay only store form/costume/gender/weather/strong (no background field exists on Pokemon yet). (Addition of background prop to pokemon #312)
• decoder/gym.go:280+ – raid boss display is copied (form/alignment/gender/costume/temp evo) but background is ignored.
• decoder/station.go:174+ – BattleDetails.BattlePokemon.PokemonDisplay maps form/costume/gender/alignment/bread mode without background.
• decoder/incident.go:180+ – rocket lineups pull PokemonDisplay.Form for slots but not background.

Aside from these, the other PokemonDisplay usages already call ExtractBackgroundFromDisplay (guard/defender displays, Pokéstop rewards/showcase entries, stationed Pokémon after your change).