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>

docs/PLAN.md

@@ -162,11 +162,20 @@ The numbered sections below keep their full scope. Each one opens with a checkli
 - The stats screen shows its three pages from BattleMonMenu and Bill's PC.
 - The reference suite compares the send-out and withdraw texts, `RestoreHealth`, `RestorePP`, `ChangeHappiness` and `CalcPlayerStats` with the original routines.
 
+## Implemented: the start menu, party menu and pack
+
+- Start opens `StartMenu` with the items `SetUpMenuItems` lists for the player's progress (POKéDEX, POKéMON, PACK, POKéGEAR, the player's name, SAVE, OPTION, EXIT) and their ROM descriptions. POKéDEX, POKéGEAR, the trainer card and OPTION give a notice; SAVE points to the automatic session saves.
+- POKéMON: the party menu with the ROM's prompts and `GetMonSubmenuItems`: field moves the Pokémon knows (from `MonMenuOptions`), STATS, SWITCH, MOVE, ITEM or MAIL, and CANCEL when there is room. STATS opens the stats screen; SWITCH asks "Move to where?" and swaps the two Pokémon; MOVE (`MoveScreenLoop`) swaps two moves with their PP; ITEM gives an item from the pack (key items and untossable items "can't be held"), swaps it with the held item or takes it back, with the pack-full checks of `TryGiveItemToPartymon` and `TakePartyItem`.
+- PACK: the Items, Balls, Key and TM pockets (left and right change pockets; there are no TMs or HMs yet), and each item's submenu chosen by its permissions and field menu (`USE`, `GIVE`, `TOSS`, `SEL`, `QUIT`). TOSS asks how many and confirms. USE follows `UseItem`: Oak's warning without a field use, "You don't have a POKéMON!" for party items without one, and `_DoItemEffect` by the item's `ItemEffects` address: Potions and the other `HealingHPAmounts` items, status healers, Full Restore, Revive and Max Revive, the bitter Energypowder, Energy Root, Heal Powder and Revival Herb, Ethers, Elixers, the MysteryBerry and PP Up. The Bicycle closes the menu and runs `Script_GetOnBike` or `Script_GetOffBike` outdoors; elsewhere Oak objects, because `wFieldMoveSucceeded` shares `wItemEffectSucceeded`'s byte.
+- PP Up keeps a quirk: `wUsePPUp` shares `wTempPP`'s byte, so `ComputeMaxPP` adds one step (a fifth of the base PP, at most 7) to the current PP as well as the maximum. Sketch and moves with three PP Ups are "maxed out".
+- The menu runs on a script draft, like the PC. Changes commit when it closes; a save made while it is open keeps the state from before it. The start menu cursor, the party menu cursor and the last pocket stay in memory between openings and are cleared after a battle, as `CleanUpBattleRAM` does. The party cursor reaches the next battle's `ChangeHappiness`.
+- Select keeps opening the Key Items shortcut, standing in for a registered item. Not ported: field moves from the menu, MAIL, SEL (registering items), moving a Pokémon's moves to another party member with left and right, item reordering with Select, evolution stones, Rare Candy, vitamins and the other field items (each gives a notice and changes nothing).
+
 ## Native battles: current state
 
 The battle core, ROM tables, encounter hooks, battle UI and whiteout hooks are present. Unit tests cover wins, escape, loss, experience, move learning and capture; reference tests compare damage, type effectiveness, stat calculation and experience curves. Browser tests drive a test-only wild encounter through the real UI: victory with level-up and move learning, escape, whiteout, catching with a nickname, keyboard and on-screen D-pad menu navigation, mid-battle backup restore, rollback of unsupported effects, switching through the party menu and a Potion from the Items pocket. Real Route 29 encounters now use the ROM's encounter tables. Only the special Kurt and Park balls remain unported among battle items.
 
-This is still not a complete new game. Full party/bag/Pokégear menus, story progression beyond Route 30 and Mr. Pokémon's house, and audio remain unfinished. The Key Items menu supports the Bicycle; the PCs store Pokémon, items and decorations. Surfing and terrain animation now have native implementations; later maps remain gated. Save slots, a Johto/Kanto atlas, Pokédex records, online Link, friends and real-world steps come later.
+This is still not a complete new game. The Pokégear, Pokédex and trainer card screens, story progression beyond Route 30 and Mr. Pokémon's house, and audio remain unfinished. The start menu opens the party menu and the pack, and the Key Items shortcut supports the Bicycle; the PCs store Pokémon, items and decorations. Surfing and terrain animation now have native implementations; later maps remain gated. Save slots, a Johto/Kanto atlas, Pokédex records, online Link, friends and real-world steps come later.
 
 ## 1. Complete the overworld foundation
 
@@ -212,8 +221,9 @@ pixel-perfect screenshots or full Celebi story support.
 
 The bedroom PC selects and puts away owned decorations, including left/right
 doll placement. Room blocks, sprites and descriptions reflect saved choices.
-The Town Map poster opens the native ROM-backed map. Start/Select opens Key
-Items; using the Bicycle follows the native outdoor/indoor rules. Browser
+The Town Map poster opens the native ROM-backed map. Select opens Key Items
+(Start now opens the start menu); using the Bicycle follows the native
+outdoor/indoor rules. Browser
 checks cover both controls and decoration flows in Chromium and WebKit.
 Full item/Pokémon PC storage and the other bag pockets belong to later work.
 
@@ -243,7 +253,7 @@ Introduce native player, party, Pokémon, inventory, money and quest models. Rea
 
 Expand script calls, choices, scene state, inventory commands and native special handlers. Translate routines reached through assembly calls into explicit native services; never fall back to emulator execution in the shipping game.
 
-Meeting Mom, Elm's introduction, the starter, the aide's Potion, Route 29, Cherrygrove, Route 30's trainers, Mr. Pokémon's house, the Cherrygrove rival battle, the return to Elm, capture, the catching tutorial, the PC, the introduction's naming and clock screens, and switching and healing items in battle run now. The opening milestone is complete within the recorded acceptance boundaries. Next: party and bag menus outside battle, MOVE PKMN W/O MAIL and evolution.
+Meeting Mom, Elm's introduction, the starter, the aide's Potion, Route 29, Cherrygrove, Route 30's trainers, Mr. Pokémon's house, the Cherrygrove rival battle, the return to Elm, capture, the catching tutorial, the PC, the introduction's naming and clock screens, and switching and healing items in battle run now. The opening milestone is complete within the recorded acceptance boundaries. The start menu, party menu and pack now run outside battle. Next: evolution, then MOVE PKMN W/O MAIL.
 
 Complete and validate the native battle engine: deterministic randomness, stats, move selection, accuracy/critical checks, damage, status, turn order, switching, fainting, experience, capture and rewards. Compare controlled seeds and states with the original, including integer rounding and overflow behavior.
 
@@ -273,7 +283,8 @@ Acceptance: main-game/postgame playthroughs, representative optional content, ba
 - [x] Adaptive canvas, live local minimap, keyboard and on-screen controls
 - [x] Save, backup export and import for the single native save
 - [x] Touch battle commands, move list, PKMN party menu, PACK (Items and Balls pockets) and naming fields
-- [ ] Party, pack, PC and Pokégear menus outside battle
+- [x] Start menu, party menu and pack outside battle (switching, moves, held items, healing and PP items, tossing, the Bicycle)
+- [ ] Pokégear, Pokédex, trainer card and options screens; MOVE PKMN W/O MAIL
 - [ ] Scalable text, configurable controls and fuller accessibility
 - [ ] Save slots with migration, atomic writes and import previews
 - [ ] Installable web app with offline app shell, safe updates and quota handling