Open Route 30 with map trainers and multi-Pokémon trainer battles

Map trainers run the ROM's TalkToTrainerScript and SeenByTrainerScript.
_CheckTrainerBattle runs before tile events at the end of each step and
on idle ticks; TrainerWalkToPlayer builds wMovementBuffer natively, and
writeobjectxy keeps the trainer where it stopped. The interpreter gains
the trainer header commands, wRunningTrainerBattleScript and hidden
items (HiddenItemScript).

Trainers with several Pokémon send out the next one through
EnemyPartyMonEntrance and FindMonInOTPartyToSwitchIntoBattle, including
its BattleRandom fallback. AI_SwitchOrTryItem, CheckAbleToSwitch and
AI_Switch are translated with their original bugs, and wPlayerUsedMoves
is recorded. The Shift-mode switch offer, trainer items, Pursuit on a
switch, Perish Song and Spikes remain refused.

Route 30 and its Berry house are enabled; Mr. Pokémon's house and
Route 31 stay closed. A refused trainer sighting does not restart until
the player moves, so a rollback cannot trap the player in view.

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

docs/ARCHITECTURE.md

@@ -48,4 +48,4 @@ Asset caches and the ROM reader remain in memory for lazy extraction. Neither RO
 
 The native viewport follows its available CSS dimensions and draws additional world tiles at a bounded pixel resolution. Beyond a map's edge it draws the connected map with the current tileset, as the original connection strips do, and the border block elsewhere. Resizing also redraws paused sessions. The local minimap caches terrain from the loaded map and updates its marker from the same world position used by the player; the Map tab shares that view. It is a current-area map, not a full region atlas. Leaving Game pauses the session and releases held input; returning requires explicit play. The reference player retains its own fixed-screen styling.
 
-`game/battle` now holds the native battle core and ROM-backed battle tables. Browser tests cover the overworld-to-battle flow using a test-only encounter fixture; Route 29 uses ROM encounter tables. Scripted single-Pokémon trainer battles share that core, with ROM trainer decoders and explicit AI support checks; test fixtures exercise these without opening new production maps. Introduce future modules with working features: `game/audio`, then `features/link` and `features/walking`. Party and bag models live in `game/party`; scripts change them only on their draft state. Rules must not import UI/browser modules. Transports and step providers must not write directly into world state.
+`game/battle` now holds the native battle core and ROM-backed battle tables. Browser tests cover the overworld-to-battle flow using a test-only encounter fixture; Route 29 uses ROM encounter tables. Trainer battles share that core, with ROM trainer decoders, the trainer's send-out and switch AI, and explicit AI support checks. Map trainers (sight and talk) are started by `game/world` and run the ROM's own trainer scripts. Introduce future modules with working features: `game/audio`, then `features/link` and `features/walking`. Party and bag models live in `game/party`; scripts change them only on their draft state. Rules must not import UI/browser modules. Transports and step providers must not write directly into world state.