feat(ai): 知识库 V2 Handler + 路由注册 + State 初始化

5 个端点：GET/POST /ai/knowledge-bases, GET/PUT/DELETE /ai/knowledge-bases/{id}
AiState 新增 knowledge_v2 字段，main.rs 初始化。

crates/erp-ai/src/module.rs

@@ -588,6 +588,27 @@ impl AiModule {
                 "/ai/knowledge/guides/{id}/re-embed",
                 axum::routing::post(crate::handler::knowledge_handler::re_embed_guide),
             )
+            // 知识库 V2 路由
+            .route(
+                "/ai/knowledge-bases",
+                axum::routing::get(crate::handler::knowledge_v2_handler::list_knowledge_bases),
+            )
+            .route(
+                "/ai/knowledge-bases",
+                axum::routing::post(crate::handler::knowledge_v2_handler::create_knowledge_base),
+            )
+            .route(
+                "/ai/knowledge-bases/{id}",
+                axum::routing::get(crate::handler::knowledge_v2_handler::get_knowledge_base),
+            )
+            .route(
+                "/ai/knowledge-bases/{id}",
+                axum::routing::put(crate::handler::knowledge_v2_handler::update_knowledge_base),
+            )
+            .route(
+                "/ai/knowledge-bases/{id}",
+                axum::routing::delete(crate::handler::knowledge_v2_handler::delete_knowledge_base),
+            )
             .route(
                 "/ai/dialysis/risk-assessment",
                 axum::routing::post(crate::handler::assess_dialysis_risk),