feat(core): add audit logging to all mutation operations

Create audit_log SeaORM entity and audit_service::record() helper.
Integrate audit recording into 35 mutation endpoints across all modules:
- erp-auth: user/role/organization/department/position CRUD (15 actions)
- erp-config: dictionary/menu/setting/numbering_rule CRUD (15 actions)
- erp-workflow: definition/instance/task operations (8 actions)
- erp-message: send/system/mark_read/delete (5 actions)

Uses fire-and-forget pattern — audit failures logged but non-blocking.

crates/erp-auth/src/service/org_service.rs

@@ -7,6 +7,8 @@ use uuid::Uuid;
 use crate::dto::{CreateOrganizationReq, OrganizationResp, UpdateOrganizationReq};
 use crate::entity::organization;
 use crate::error::{AuthError, AuthResult};
+use erp_core::audit::AuditLog;
+use erp_core::audit_service;
 use erp_core::error::check_version;
 use erp_core::events::EventBus;
 
@@ -110,6 +112,13 @@ impl OrgService {
             serde_json::json!({ "org_id": id, "name": req.name }),
         ));
 
+        audit_service::record(
+            AuditLog::new(tenant_id, Some(operator_id), "organization.create", "organization")
+                .with_resource_id(id),
+            db,
+        )
+        .await;
+
         Ok(OrganizationResp {
             id,
             name: req.name.clone(),
@@ -177,6 +186,13 @@ impl OrgService {
             .await
             .map_err(|e| AuthError::Validation(e.to_string()))?;
 
+        audit_service::record(
+            AuditLog::new(tenant_id, Some(operator_id), "organization.update", "organization")
+                .with_resource_id(id),
+            db,
+        )
+        .await;
+
         Ok(OrganizationResp {
             id: updated.id,
             name: updated.name.clone(),
@@ -235,6 +251,14 @@ impl OrgService {
             tenant_id,
             serde_json::json!({ "org_id": id }),
         ));
+
+        audit_service::record(
+            AuditLog::new(tenant_id, Some(operator_id), "organization.delete", "organization")
+                .with_resource_id(id),
+            db,
+        )
+        .await;
+
         Ok(())
     }
 }