feat(dialysis+workflow): 透析会话 BPMN 工作流集成

- dialysis_record 新增 workflow_instance_id 列，关联工作流实例
- 种子 dialysis_session BPMN 流程定义：透前评估→上机确认→透中监测→透后评估→医生审核
- 事件驱动编排器：dialysis.record.created → 自动启动 BPMN 工作流
- 工作流启动后自动回写 instance_id 到透析记录
- 编排器在 erp-server 层实现（遵循星型依赖架构）

crates/erp-server/src/main.rs

@@ -1,5 +1,6 @@
 mod config;
 mod db;
+mod dialysis_workflow;
 mod handlers;
 mod middleware;
 mod outbox;
@@ -295,6 +296,11 @@ async fn main() -> anyhow::Result<()> {
                     tracing::warn!(error = %e, "Failed to seed AI workflow definitions");
                 }
 
+                // Seed dialysis session workflow definition
+                if let Err(e) = dialysis_workflow::seed_dialysis_session_workflow(&db, new_tenant_id, new_tenant_id).await {
+                    tracing::warn!(error = %e, "Failed to seed dialysis session workflow");
+                }
+
                 new_tenant_id
             }
         }
@@ -425,6 +431,10 @@ async fn main() -> anyhow::Result<()> {
     erp_plugin::notification::start_notification_listener(db.clone(), event_bus.clone());
     tracing::info!("Plugin notification listener started");
 
+    // Start dialysis workflow orchestrator (dialysis.record.created → BPMN workflow)
+    dialysis_workflow::start_dialysis_workflow_orchestrator(db.clone(), event_bus.clone());
+    tracing::info!("Dialysis workflow orchestrator started");
+
     // Start outbox relay (LISTEN/NOTIFY + fallback poll for pending domain events)
     outbox::start_outbox_relay(db.clone(), event_bus.clone(), config.database.url.clone());
     tracing::info!("Outbox relay started");