Port field moves from the menu, SEL with Select, and moving Pokémon in Bill's PC

Field moves chosen in the party menu run their original checks and the
ROM's from-menu scripts (Cut, Surf, Strength, Flash, Whirlpool, Waterfall,
Sweet Scent), and Softboiled and Milk Drink share HP. SEL registers a key
item that Select then uses, replacing the Key Items shortcut, and Bill's
PC moves Pokémon between the party and every box.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/game/battle/constants.ts

@@ -256,6 +256,8 @@ export const C = {
   KEY_ITEM_POCKET: 2,
   TM_HM_POCKET: 3,
   PP_UP: 0x3e,
+  SOFTBOILED: 0x87,
+  MILK_DRINK: 0xd0,
   RARE_CANDY: 0x20,
   HP_UP: 0x1a,
   PROTEIN: 0x1b,