fix(c2c): 修复水单上传权限、手机号、卖方ID、资产显示

- Dockerfile: 用 su-exec 模式解决 Docker volume 权限问题
- JWT guard: 从 token 提取 phone 字段
- 订单详情: 新增卖方ID显示
- C2C市场页: 修复资产概览两列重复显示 availableCash，
  改为左列显示可用积分股、右列显示可用积分值

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/services/trading-service/Dockerfile

@@ -22,9 +22,9 @@ FROM node:20-alpine AS runner
 RUN addgroup --system --gid 1001 nodejs && \
     adduser --system --uid 1001 -G nodejs nestjs
 
-RUN apk add --no-cache curl tzdata openssl
+RUN apk add --no-cache curl tzdata openssl su-exec
 
-RUN mkdir -p /app /app/uploads/c2c-proofs && chown -R nestjs:nodejs /app
+RUN mkdir -p /app && chown nestjs:nodejs /app
 WORKDIR /app
 
 USER nestjs
@@ -37,7 +37,9 @@ RUN DATABASE_URL="postgresql://user:pass@localhost:5432/db" npx prisma generate
 
 COPY --chown=nestjs:nodejs --from=builder /app/dist ./dist
 
-RUN printf '#!/bin/sh\nset -e\necho "Running database migrations..."\nnpx prisma migrate deploy\necho "Starting application..."\nexec node dist/main.js\n' > /app/start.sh && chmod +x /app/start.sh
+# entrypoint 以 root 启动 → 修复 volume 权限 → 降权到 nestjs 运行
+USER root
+RUN printf '#!/bin/sh\nset -e\n# 修复 Docker volume 挂载权限（volume 首次由 root 创建）\nmkdir -p /app/uploads/c2c-proofs\nchown -R nestjs:nodejs /app/uploads\n# 以 nestjs 用户运行\necho "Running database migrations..."\nsu-exec nestjs npx prisma migrate deploy\necho "Starting application..."\nexec su-exec nestjs node dist/main.js\n' > /app/start.sh && chmod +x /app/start.sh
 
 ENV NODE_ENV=production
 ENV TZ=Asia/Shanghai

frontend/mining-app/lib/presentation/pages/c2c/c2c_market_page.dart

@@ -127,12 +127,12 @@ class _C2cMarketPageState extends ConsumerState<C2cMarketPage>
               crossAxisAlignment: CrossAxisAlignment.start,
               children: [
                 Text(
-                  '可用积分值',
+                  '可用积分股',
                   style: TextStyle(fontSize: 12, color: AppColors.textSecondaryOf(context)),
                 ),
                 const SizedBox(height: 4),
                 Text(
-                  formatAmount(availableCash),
+                  formatAmount(availableShares),
                   style: const TextStyle(
                     fontSize: 18,
                     fontWeight: FontWeight.bold,