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/course/index.html

@@ -137,6 +137,12 @@
         <p>总架构、数据流、分 Agent 亮点、Demo 动线、诚实边界、Q&amp;A 锚点——与交互课同步。</p>
         <span class="tag">docs/答辩 · 可打印提纲</span>
       </a>
+      <a class="card" href="../答辩/DEMO-SOP-答辩全流程.md">
+        <span class="card-accent" style="background:#1F6280"></span>
+        <h2>答辩 Demo 全流程 SOP</h2>
+        <p>给人看的逐步演示：6～25 分钟三档路线、四角色账号、每步<strong>亮点+口述句</strong>；链问数/风控分册。</p>
+        <span class="tag">Markdown · 答辩主脚本</span>
+      </a>
     </div>
 
     <p class="section-label">架构治理 · ADR 与不变量</p>