feat(ai): 知识库 V2 菜单迁移 + 文本切片器 + 前端路由权限

- 新增迁移 000168：在 AI 知识库同级添加「知识库 V2」菜单，绑定 admin 角色
- 新增 document/chunker.rs：固定大小 + overlap 文本切片器（5 单元测试）
- 前端 routeConfig 添加 /health/ai-knowledge-v2 权限声明
- App.tsx validateRouteCoverage 补充 v2 路径

apps/web/src/App.tsx

@@ -258,7 +258,7 @@ export default function App() {
       "/health/follow-up-records", "/health/consultations",
       "/health/points-rules", "/health/points-products", "/health/points-orders",
       "/health/offline-events", "/health/ai-prompts", "/health/ai-analysis",
-      "/health/ai-usage", "/health/ai-config", "/health/ai-knowledge", "/health/alerts", "/health/alert-dashboard",
+      "/health/ai-usage", "/health/ai-config", "/health/ai-knowledge", "/health/ai-knowledge-v2", "/health/alerts", "/health/alert-dashboard",
       "/ai/chat",
       "/health/alert-rules", "/health/devices", "/health/realtime-monitor",
       "/health/oauth-clients", "/health/dialysis", "/health/action-inbox",

apps/web/src/routeConfig.ts

@@ -151,6 +151,10 @@ const ENTRIES: RoutePermissionEntry[] = [
     path: "/health/ai-knowledge",
     permissions: ["ai.knowledge.list", "ai.knowledge.manage"],
   },
+  {
+    path: "/health/ai-knowledge-v2",
+    permissions: ["ai.knowledge.list", "ai.knowledge.manage"],
+  },
 
   // ===== 健康管理 — 积分商城 =====
   {