refactor: overhaul homepage and app structure

Simplify homepage, show chapter counts, display directory, trim bottom nav, in-page match feature, move marketing content, and enhance "My" page.

#VERCEL_SKIP

Co-authored-by: undefined <undefined+undefined@users.noreply.github.com>

开发文档/7、数据库/数据库管理规范.md

@@ -47,7 +47,7 @@
 3.  **结构可视化**：用 Mermaid 生成 ER 图。
 
 ### 示例 Mermaid (ER图)
-```mermaid
+\`\`\`mermaid
 erDiagram
     User ||--o{ Order : places
     User ||--o{ TrafficPool : owns
@@ -59,4 +59,4 @@ erDiagram
         string orderId
         float amount
     }
-```
+\`\`\`