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/migration/src/lib.rs

@@ -113,6 +113,7 @@ mod m20260504_000110_alter_critical_alerts_version_i32;
 mod m20260505_000111_create_care_plan;
 mod m20260505_000112_create_shift_management;
 mod m20260505_000113_create_ble_gateways;
+mod m20260505_000114_dialysis_record_add_workflow_instance;
 
 pub struct Migrator;
 
@@ -233,6 +234,7 @@ impl MigratorTrait for Migrator {
             Box::new(m20260505_000111_create_care_plan::Migration),
             Box::new(m20260505_000112_create_shift_management::Migration),
             Box::new(m20260505_000113_create_ble_gateways::Migration),
+            Box::new(m20260505_000114_dialysis_record_add_workflow_instance::Migration),
         ]
     }
 }

crates/erp-server/migration/src/m20260505_000114_dialysis_record_add_workflow_instance.rs

@@ -0,0 +1,33 @@
+use sea_orm_migration::prelude::*;
+
+#[derive(DeriveMigrationName)]
+pub struct Migration;
+
+#[async_trait::async_trait]
+impl MigrationTrait for Migration {
+    async fn up(&self, manager: &SchemaManager) -> Result<(), DbErr> {
+        manager
+            .alter_table(
+                Table::alter()
+                    .table(Alias::new("dialysis_record"))
+                    .add_column(
+                        ColumnDef::new(Alias::new("workflow_instance_id"))
+                            .uuid()
+                            .null(),
+                    )
+                    .to_owned(),
+            )
+            .await
+    }
+
+    async fn down(&self, manager: &SchemaManager) -> Result<(), DbErr> {
+        manager
+            .alter_table(
+                Table::alter()
+                    .table(Alias::new("dialysis_record"))
+                    .drop_column(Alias::new("workflow_instance_id"))
+                    .to_owned(),
+            )
+            .await
+    }
+}