Port the remaining battle items, the stats screen and hBattleTurn at the menu

- Run every non-ball item effect usable in battle from the ROM's
  ItemEffects: Full Restore, revives, bitter medicine, Bitter Berry, Ethers
  and Elixers, X items, X Accuracy, Guard Spec, Dire Hit and Poké Doll.
- Read happiness changes from HappinessChanges, including the larger
  level-up gain where a Pokémon was caught.
- Model hBattleTurn at the battle menu, including the trainer AI's writes,
  and drop the status-heal refusal.
- Port the stats screen for battles and Bill's PC.
- Compare the send-out and withdraw texts, RestoreHealth, RestorePP,
  ChangeHappiness and CalcPlayerStats with the original routines.

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

scripts/check-reference.mjs

@@ -202,8 +202,8 @@ for (const [key, symbol] of Object.entries(ramNames)) {
   if (!match || Number(match[1]) !== ram.get(symbol))
     throw new Error(`Profile RAM mismatch: ${key} / ${symbol}`);
 }
-// BATTLE, OVERWORLD, PC and INTRO entries are keyed by their PRET labels.
-for (const table of ["BATTLE", "OVERWORLD", "PC", "INTRO"]) {
+// BATTLE, OVERWORLD, PC, INTRO and STATS entries are keyed by their PRET labels.
+for (const table of ["BATTLE", "OVERWORLD", "PC", "INTRO", "STATS"]) {
   const block = new RegExp(`export const ${table} = \\{([\\s\\S]*?)\\} as const;`).exec(profile)?.[1];
   if (!block) throw new Error(`${table} symbol table is missing.`);
   for (const [, quoted, bare, literal] of block.matchAll(/^\s+(?:"([^"]+)"|(\w+)):\s*(0x[0-9a-f]+),/gm)) {