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 <[email protected]>

tests/services/test_usage_queue_events.py

@@ -378,6 +378,7 @@ async def test_event_to_record_body_deserialization(monkeypatch: Any) -> None:
     event = build_usage_event(
         event_type=UsageEventType.COMPLETED,
         request_id="req-body-test",
+        timestamp_ms=1_700_000_000_123,
         data={
             "user_id": "user-1",
             "api_key_id": "key-1",
@@ -396,6 +397,7 @@ async def test_event_to_record_body_deserialization(monkeypatch: Any) -> None:
     assert record["request_body"]["messages"][0]["content"] == "hello"
     assert isinstance(record["response_body"], dict)
     assert record["response_body"]["choices"][0]["message"]["content"] == "hi"
+    assert record["finalized_at"] is not None
 
 
 @pytest.mark.asyncio