feat: implement on_tenant_created/deleted hooks and update ErpModule trait

- ErpModule trait hooks now accept db and event_bus parameters
- AuthModule.on_tenant_created: seeds default roles, permissions,
  and admin user for new tenants using existing seed_tenant_auth()
- AuthModule.on_tenant_deleted: soft-deletes all users for the tenant
- Updated all other modules (config, workflow, message) to match
  the new trait signature

crates/erp-config/src/module.rs

@@ -121,11 +121,20 @@ impl ErpModule for ConfigModule {
 
     fn register_event_handlers(&self, _bus: &EventBus) {}
 
-    async fn on_tenant_created(&self, _tenant_id: Uuid) -> AppResult<()> {
+    async fn on_tenant_created(
+        &self,
+        _tenant_id: Uuid,
+        _db: &sea_orm::DatabaseConnection,
+        _event_bus: &EventBus,
+    ) -> AppResult<()> {
         Ok(())
     }
 
-    async fn on_tenant_deleted(&self, _tenant_id: Uuid) -> AppResult<()> {
+    async fn on_tenant_deleted(
+        &self,
+        _tenant_id: Uuid,
+        _db: &sea_orm::DatabaseConnection,
+    ) -> AppResult<()> {
         Ok(())
     }