feat: Phase 2 — 战斗引擎 @pkmn 薄适配层

- 安装 @pkmn/protocol @pkmn/client @pkmn/view
- 新建 battle/types.ts: BattleState, BattlePokemon, BattleEvent, PlayerAction 等
- 新建 battle/adapter.ts: Creature→PokemonSet 转换, 野生对手生成
- 新建 battle/engine.ts: createBattle() + executeTurn() 薄封装 @pkmn/sim
- 新建 battle/handler.ts: @pkmn/protocol Handler→BattleEvent 转换
- 新建 battle/ai.ts: 随机合法招式 AI 决策
- 新建 battle/settlement.ts: 战后结算 XP/EV/升级/进化/招式学习
- 新建 battle/index.ts: 统一导出

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/pokemon/package.json

@@ -5,5 +5,9 @@
   "type": "module",
   "main": "./src/index.ts",
   "types": "./src/index.ts",
-  "dependencies": {}
+  "dependencies": {
+    "@pkmn/client": "^0.7.2",
+    "@pkmn/protocol": "^0.7.2",
+    "@pkmn/view": "^0.7.2"
+  }
 }