feat(health): 批量随访操作 — batch_create/assign/complete 三个端点

POST /health/follow-up-tasks/batch-create — 多患者同配置批量创建
POST /health/follow-up-tasks/batch-assign — 批量分配负责人
POST /health/follow-up-tasks/batch-complete — 批量标记完成

含参数校验（上限 100）、部分失败报告、事件发布、审计日志。

crates/erp-health/src/module.rs

@@ -289,6 +289,19 @@ impl HealthModule {
                 "/health/follow-up-records",
                 axum::routing::get(follow_up_handler::list_records),
             )
+            // 随访批量操作
+            .route(
+                "/health/follow-up-tasks/batch-create",
+                axum::routing::post(follow_up_handler::batch_create_tasks),
+            )
+            .route(
+                "/health/follow-up-tasks/batch-assign",
+                axum::routing::post(follow_up_handler::batch_assign_tasks),
+            )
+            .route(
+                "/health/follow-up-tasks/batch-complete",
+                axum::routing::post(follow_up_handler::batch_complete_tasks),
+            )
             // 咨询管理
             .route(
                 "/health/consultation-sessions",