Mod: mining rig, graphics cards, trading terminal, nightly settlement

First playable slice, tested in game on the test save:
- Network upgrade "Mining Access" (300) delivers a trading terminal, a
  mining rig and an RZX 50.
- The rig is a machine with a battery slot and four card slots; each night
  it draws its total power from the battery and its cards mine PSCoin.
  Cards show hashrate, power draw and condition, wear every night and can
  burn out. All state lives on item tags or in the mod save data.
- Trading terminal with wallet, trade (four pairs, deposit credits as CRC,
  withdraw CRC through the compliance desk) and report pages.
- Nightly log lines; exchange opening and halving news on the paper.
- English and Chinese text; sprites generated by art/sprites.py.

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

CHANGELOG.md

@@ -4,3 +4,5 @@
 
 - 纯逻辑层：带种子的随机数、资产登记、地址账本（污点与成本随币走）、恒定乘积交易对、挖矿（显卡、矿机、全网算力、减半、损耗与暴毙）。
 - 纯逻辑层：市场（价格锚、情绪、游戏事件冲击、NPC 大户、多交易对套利回归、当日均价），三种稳定币（CRC 脱锚与减记、CRT 脱锚与冻结概率、CRA 补贴池与死亡螺旋），合规出金与 AML（大额与累计阈值、污点比例、轻度与重度命中、只对收益计税）。
+- mod 本体（第一阶段的第一部分）：人脉网络"矿业渠道"（300）交付交易终端、矿架和一张 RZX 50；矿架是带电池槽和 4 个显卡槽的机器，每晚从电池扣电挖 PSCoin；显卡按型号显示算力、耗电与健康度，每晚损耗并可能烧毁；交易终端有钱包、交易（四个交易对、存入信用点、提取 CRC 过合规审查）、报告三页；夜间结算写晨间日志；PSCoin 交易所开业与减半上报纸；状态存进游戏的 mod 存档数据。中英双语。
+- 物品图：art/sprites.py 生成显卡（Probidia、PMD、烧毁）、矿架、交易终端。