feat(core): implement event outbox persistence

Add domain_events migration and SeaORM entity. Modify EventBus::publish
to persist events before broadcasting (best-effort: DB failure logs
warning but still broadcasts in-memory). Update all 19 publish call
sites across 4 crates to pass db reference.

Add outbox relay background task that polls pending events every 5s
and re-broadcasts them, ensuring no events are lost on server restart.

crates/erp-core/src/events.rs

@@ -1,9 +1,12 @@
-use chrono::{DateTime, Utc};
+use chrono::Utc;
+use sea_orm::{ActiveModelTrait, Set};
 use serde::{Deserialize, Serialize};
 use tokio::sync::broadcast;
 use tracing::{error, info};
 use uuid::Uuid;
 
+use crate::entity::domain_event;
+
 /// 领域事件
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct DomainEvent {
@@ -11,7 +14,7 @@ pub struct DomainEvent {
     pub event_type: String,
     pub tenant_id: Uuid,
     pub payload: serde_json::Value,
-    pub timestamp: DateTime<Utc>,
+    pub timestamp: chrono::DateTime<Utc>,
     pub correlation_id: Uuid,
 }
 
@@ -46,11 +49,40 @@ impl EventBus {
         Self { sender }
     }
 
-    /// 发布事件
-    pub fn publish(&self, event: DomainEvent) {
-        info!(event_type = %event.event_type, event_id = %event.id, "Event published");
+    /// 发布事件：先持久化到 domain_events 表，再内存广播。
+    ///
+    /// 持久化失败时仅记录 warning，仍然广播（best-effort）。
+    pub async fn publish(&self, event: DomainEvent, db: &sea_orm::DatabaseConnection) {
+        // 持久化到 domain_events 表
+        let model = domain_event::ActiveModel {
+            id: Set(event.id),
+            tenant_id: Set(event.tenant_id),
+            event_type: Set(event.event_type.clone()),
+            payload: Set(Some(event.payload.clone())),
+            correlation_id: Set(Some(event.correlation_id)),
+            status: Set("published".to_string()),
+            attempts: Set(0),
+            last_error: Set(None),
+            created_at: Set(event.timestamp),
+            published_at: Set(Some(Utc::now())),
+        };
+
+        match model.insert(db).await {
+            Ok(_) => {}
+            Err(e) => {
+                tracing::warn!(event_id = %event.id, error = %e, "领域事件持久化失败");
+            }
+        }
+
+        // 内存广播
+        self.broadcast(event);
+    }
+
+    /// 仅内存广播（不持久化，用于内部测试等场景）。
+    pub fn broadcast(&self, event: DomainEvent) {
+        info!(event_type = %event.event_type, event_id = %event.id, "Event broadcast");
         if let Err(e) = self.sender.send(event) {
-            error!("Failed to publish event: {}", e);
+            error!("Failed to broadcast event: {}", e);
         }
     }