feat: enhance response serialization for compact mode

- Added support for preserving native response.compaction payloads when compact serialization is requested in `serializeResponsesFinalPayload`.
- Implemented serialization of compact mode as `response.compaction` instead of an ordinary response object.
- Introduced a new type `ResponsesFinalSerializationMode` to manage serialization modes.
- Refactored `serializeResponsesFinalPayload` to handle different serialization modes and usage payloads.
- Added tests to ensure correct behavior for compact serialization and preservation of upstream payloads.
- Updated favicon assets and documentation configuration for VitePress.

docs/configuration.md

@@ -87,12 +87,19 @@ Metapi 的路由引擎按多因子加权选择最优通道。
 
 ### 路由预设建议
 
-| 场景 | COST_WEIGHT | BALANCE_WEIGHT | USAGE_WEIGHT |
-|------|:-----------:|:--------------:|:------------:|
-| **成本优先** | 0.7 | 0.2 | 0.1 |
-| **均衡（默认）** | 0.4 | 0.3 | 0.3 |
-| **稳定优先** | 0.2 | 0.5 | 0.3 |
-| **轮转均匀** | 0.1 | 0.1 | 0.8 |
+| 场景 | COST_WEIGHT | BALANCE_WEIGHT | USAGE_WEIGHT | 说明 |
+|------|:-----------:|:--------------:|:------------:|------|
+| **成本优先** | 0.7 | 0.2 | 0.1 | 适合预算敏感场景，总是选最便宜的通道 |
+| **均衡（默认）** | 0.4 | 0.3 | 0.3 | 兼顾成本、余额和负载均衡，推荐大多数用户 |
+| **稳定优先** | 0.2 | 0.5 | 0.3 | 适合生产环境，优先选余额充足的通道避免中断 |
+| **轮转均匀** | 0.1 | 0.1 | 0.8 | 适合测试场景，尽量让每个通道都被使用到 |
+
+**调参建议：**
+
+- 如果某个站点总是被选中导致余额很快耗尽 → 调高 `BALANCE_WEIGHT`
+- 如果你有几个很便宜的站点想优先用 → 调高 `COST_WEIGHT`
+- 如果你想让请求均匀分散到所有站点 → 调高 `USAGE_WEIGHT`
+- 如果你需要对特定项目偏好某个站点 → 使用[下游 API Key 的 `siteWeightMultipliers`](#下游-api-key-策略) 而非调全局权重
 
 ## 代理日志保留
 
@@ -209,3 +216,5 @@ Metapi 的路由引擎按多因子加权选择最优通道。
 
 - [部署指南](./deployment.md) — Docker Compose 与反向代理
 - [客户端接入](./client-integration.md) — 对接下游应用
+- [上游接入](./upstream-integration.md) — 添加和管理上游平台
+- [运维手册](./operations.md) — 备份、日志与健康检查