Port the start menu, the party menu and the pack outside battle

Start opens the original start menu. POKéMON shows the party with the
Pokémon submenu (stats, switching, move order, held items); PACK shows the
four pockets with the field item effects for healing, PP and the Bicycle,
plus giving and tossing. The menu runs on a script draft, and its cursors
persist until a battle clears them. Select keeps the Key Items shortcut.

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, INTRO and STATS entries are keyed by their PRET labels.
-for (const table of ["BATTLE", "OVERWORLD", "PC", "INTRO", "STATS"]) {
+// BATTLE, OVERWORLD, PC, INTRO, STATS and MENU entries are keyed by their PRET labels.
+for (const table of ["BATTLE", "OVERWORLD", "PC", "INTRO", "STATS", "MENU"]) {
   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)) {
@@ -323,6 +323,8 @@ for (const [, block] of battleConstants.matchAll(/export const \w+ = \{([\s\S]*?
       throw new Error(`Battle constant mismatch: ${name} is ${literal}, PRET has ${expected}`);
   }
 }
+if (!profile.includes(`pokegear: ${pretConstants.get("ENGINE_POKEGEAR")},`))
+  throw new Error("ENGINE_POKEGEAR does not match the reference.");
 if (!profile.includes(`pokedex: ${pretConstants.get("ENGINE_POKEDEX")},`))
   throw new Error("ENGINE_POKEDEX does not match the reference.");
 if (!profile.includes(`allFruitTrees: ${pretConstants.get("ENGINE_ALL_FRUIT_TREES")},`))