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/role_service.rs

@@ -8,6 +8,8 @@ use crate::dto::{PermissionResp, RoleResp};
 use crate::entity::{permission, role, role_permission};
 use crate::error::AuthError;
 use crate::error::AuthResult;
+use erp_core::audit::AuditLog;
+use erp_core::audit_service;
 use erp_core::error::check_version;
 use erp_core::events::EventBus;
 use erp_core::types::Pagination;
@@ -131,6 +133,13 @@ impl RoleService {
             serde_json::json!({ "role_id": id, "code": code }),
         ));
 
+        audit_service::record(
+            AuditLog::new(tenant_id, Some(operator_id), "role.create", "role")
+                .with_resource_id(id),
+            db,
+        )
+        .await;
+
         Ok(RoleResp {
             id,
             name: name.to_string(),
@@ -180,6 +189,13 @@ impl RoleService {
             .await
             .map_err(|e| AuthError::Validation(e.to_string()))?;
 
+        audit_service::record(
+            AuditLog::new(tenant_id, Some(operator_id), "role.update", "role")
+                .with_resource_id(id),
+            db,
+        )
+        .await;
+
         Ok(RoleResp {
             id: updated.id,
             name: updated.name.clone(),
@@ -227,6 +243,14 @@ impl RoleService {
             tenant_id,
             serde_json::json!({ "role_id": id }),
         ));
+
+        audit_service::record(
+            AuditLog::new(tenant_id, Some(operator_id), "role.delete", "role")
+                .with_resource_id(id),
+            db,
+        )
+        .await;
+
         Ok(())
     }