feat(demo): playable G/question demo per World-as-Market §9 (codex loop 收敛)

把 demo/index.html mock 从旧 ore 模型升级为 World-as-Market「万物皆答题 + 双币」
最小可演版（codex 实现 → codex 两轮冷审 → 修 → 收敛，无 Blocker/Important）：

- StoreProvider 加 questions/worldTreasury/worldEvents；resolveMarket→resolveQuestion alias
- MarketDetail→QuestionModal：header kind/difficulty/currency/status；
  MATH/低难 STATE = Answer card(真本地安全表达式求值,非 mock/非 eval)；
  ORACLE/高难 STATE = G bet 面板
- 硬不变量 H1：currency=G 市场结算走 G 计价池、移除 ORE_POOL_CAP clamp
  (G 派彩不再被静默吞)；无 ore→G 兑换路径
- payout 区拆显 World fee/protocol tax/burn/event pool；receipt 标 market-wide G split
- MyAgent quick actions→QuestionActionCard(Harvest/Build/Raid/Bet + 难度条)
- Landing/MyAgent World Treasury meter + trigger 捷径(World Cup/Ore Rush/Boss)，
  带 treasury 余额 guard(不足拒绝触发、不递增阈值)；Lore WORLD EVENTS timeline
- interaction-logic.json 同步新动作(answerQuestion/placeGBet/resolveQuestion/
  triggerWorldEvent)+ G no-cap/treasury split/世界事件 flow；interaction.test.mjs 28/28
- index.local.html(LAN vendor 版)同步；两文件 JSX babel transform 校验通过

六路由全保留，未破坏 Arena/Lore/onboard/AgentMind/legacy ore path。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: keanji-x