feat: 强化用量计费状态机，新增钱包每日消费汇总分类账

- 将 usage.billing_status 默认值从 settled 改为 pending，完善
  pending -> settled/void 的状态转换逻辑，确保终态不可逆
- 新增 WalletDailyUsageLedger 模型和聚合服务，按账单日汇总
  每个钱包的消费金额、请求数和 token 用量
- 前端钱包中心页面集成每日消费流水展示，支持与充值记录混合
  排序和分页
- 新增两个数据库迁移：修复历史数据状态一致性、创建每日汇总表
- 补充计费状态机单元测试

Closes #218

Co-authored-by: LewisPen <LewisPen@nyadoo.com>

tests/services/test_video_finalize.py

@@ -54,8 +54,8 @@ def _make_db() -> MagicMock:
     usage_obj = SimpleNamespace(
         id="usage-1",
         request_id="req-1",
-        billing_status="settled",  # finalize_submitted already settled
-        request_metadata=None,  # no billing_updated_at yet
+        billing_status="pending",
+        request_metadata=None,
     )
 
     q_usage = MagicMock()