feat(nav): Implement historical NAV tracking and enhance product API

- Added `list_nav_history` method in `CoreReadOnlyRepository` to retrieve historical NAV data for products over a specified number of days.
- Introduced `get_nav_history` endpoint in `product_service` to return historical NAV sequences, improving product data accessibility.
- Updated `products.py` to include new API endpoint for fetching NAV history, ensuring compliance with access control.
- Enhanced `ready.py` to include a health check for the new functionality, ensuring system readiness.
- Updated documentation to reflect the new testing baseline of 833 passed tests, indicating improved stability and functionality across the application.

This update significantly enhances the product API by providing access to historical NAV data, improving user insights into product performance.

docs/memory/REQUIREMENTS.md

@@ -60,7 +60,7 @@
 | C-02 | 产品规则咨询 | fin_product RAG + 免责 | **已实现** · Wave1~2 | — |
 | C-03 | 政策/FAQ | fin_policy / fin_faq RAG | **已实现** · Wave1~2 | — |
 | C-04 | 亏损阈值提醒 | `customer_threshold_config` + 持仓查询追加提醒 | **已实现（2026-09-10）** · `threshold_service` | ~~T-40~~ |
-| C-05 | 产品净值 | Core 最新净值快照；禁止实时盘口 | **已实现（2026-09-10）** · `nav_query`；「实时净值」reject · **无 Chat 历史走势曲线**；统计趋势见问数 self 域（合并说明 §9.6） | ~~T-40~~ |
+| C-05 | 产品净值 | Core 最新净值快照；禁止实时盘口 | **已实现（2026-09-10）** · Chat `nav_query` · **平台 `GET …/nav/history` + 行情详情页近一年曲线（2026-09-11）** · Chat 仍无历史走势 Tool · Phase B 外部 sync 未做 | ~~T-40~~ |
 | C-07 | 风评查询 / 重测引导 | Core L0；重测引导 App/网点 | **部分已实现** · 无 Agent 内问卷 | T-41 |
 | C-08 | 配置目标 | L1 槽 `allocation_target` | **部分已实现** · 无偏离检测/调仓 | T-41 |
 | C-11 | 适当性匹配说明 | 非营销推荐；联动 R-02 | **部分已实现** · 「我能买什么」→ suitability；「推荐稳赚」仍 reject | T-42 |