fix(health): 工作台 UNION ALL 排序 + 团队概览 display_name NULL 处理

- UNION ALL 查询包装子查询解决 PostgreSQL ORDER BY 限制
- get_team_overview 的 display_name 改为 Option<String> 防止 NULL 解码失败

crates/erp-health/src/service/action_inbox_service.rs

@@ -302,7 +302,7 @@ pub async fn list_action_items(
     let union_sql = segments.join("\n UNION ALL\n");
 
     let data_sql = format!(
-        r#"{union_sql}
+        r#"SELECT * FROM ({union_sql}) sub
         ORDER BY
           CASE priority_raw WHEN 'high' THEN 1 WHEN 'urgent' THEN 1 WHEN 'medium' THEN 2 ELSE 3 END,
           created_at DESC
@@ -833,7 +833,7 @@ pub async fn get_team_overview(
     #[derive(Debug, FromQueryResult)]
     struct MemberRow {
         user_id: Uuid,
-        display_name: String,
+        display_name: Option<String>,
         title: String,
         pending_count: i64,
         completed_count: i64,
@@ -875,7 +875,7 @@ pub async fn get_team_overview(
             };
             TeamMemberOverview {
                 user_id: m.user_id,
-                name: m.display_name,
+                name: m.display_name.unwrap_or_default(),
                 title: m.title,
                 pending_count: m.pending_count as u64,
                 completed_count: m.completed_count as u64,