test: add 149 unit tests across core, auth, config, message crates

Test coverage increased from ~34 to 183 tests (zero failures):

- erp-core (21): version check, pagination, API response, error mapping
- erp-auth (39): org tree building, DTO validation, error conversion,
  password hashing, user model mapping
- erp-config (57): DTO validation, numbering reset logic, menu tree
  building, error conversion. Fixed BatchSaveMenusReq nested validation
- erp-message (50): DTO validation, template rendering, query defaults,
  error conversion
- erp-workflow (16): unchanged (parser + expression tests)

All tests are pure unit tests requiring no database.

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

@@ -393,7 +393,7 @@ impl UserService {
 }
 
 /// Convert a SeaORM user Model and its role DTOs into a UserResp.
-fn model_to_resp(m: &user::Model, roles: Vec<RoleResp>) -> UserResp {
+pub(crate) fn model_to_resp(m: &user::Model, roles: Vec<RoleResp>) -> UserResp {
     UserResp {
         id: m.id,
         username: m.username.clone(),
@@ -406,3 +406,82 @@ fn model_to_resp(m: &user::Model, roles: Vec<RoleResp>) -> UserResp {
         version: m.version,
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use chrono::Utc;
+    use uuid::Uuid;
+
+    use crate::dto::RoleResp;
+    use crate::entity::user;
+
+    use super::*;
+
+    fn make_user_model(
+        id: Uuid,
+        tenant_id: Uuid,
+        username: &str,
+        status: &str,
+        version: i32,
+    ) -> user::Model {
+        user::Model {
+            id,
+            tenant_id,
+            username: username.to_string(),
+            email: None,
+            phone: None,
+            display_name: None,
+            avatar_url: None,
+            status: status.to_string(),
+            last_login_at: None,
+            created_at: Utc::now(),
+            updated_at: Utc::now(),
+            created_by: Uuid::now_v7(),
+            updated_by: Uuid::now_v7(),
+            deleted_at: None,
+            version,
+        }
+    }
+
+    #[test]
+    fn model_to_resp_maps_basic_fields() {
+        let id = Uuid::now_v7();
+        let tid = Uuid::now_v7();
+        let m = make_user_model(id, tid, "alice", "active", 1);
+        let resp = model_to_resp(&m, vec![]);
+        assert_eq!(resp.id, id);
+        assert_eq!(resp.username, "alice");
+        assert_eq!(resp.status, "active");
+        assert_eq!(resp.version, 1);
+        assert!(resp.roles.is_empty());
+    }
+
+    #[test]
+    fn model_to_resp_includes_roles() {
+        let id = Uuid::now_v7();
+        let tid = Uuid::now_v7();
+        let m = make_user_model(id, tid, "bob", "active", 2);
+        let roles = vec![
+            RoleResp {
+                id: Uuid::now_v7(),
+                name: "管理员".to_string(),
+                code: "admin".to_string(),
+                description: None,
+                is_system: true,
+                version: 1,
+            },
+            RoleResp {
+                id: Uuid::now_v7(),
+                name: "用户".to_string(),
+                code: "user".to_string(),
+                description: None,
+                is_system: false,
+                version: 1,
+            },
+        ];
+        let resp = model_to_resp(&m, roles);
+        assert_eq!(resp.roles.len(), 2);
+        assert_eq!(resp.roles[0].code, "admin");
+        assert_eq!(resp.version, 2);
+    }
+}