fix(aiot): 修复告警 SQL 引用不存在的 gb_name 列

- queryByAlertId/queryList 的 COALESCE 去掉 sp.gb_name（该列属于
  device_channel 表，不在 stream_proxy 表中），改用 sp.name
- 新增轻量 countByAlertId 方法，save() 去重改用 COUNT 查询
  避免触发带 JOIN 的复杂 SQL

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/main/java/com/genersoft/iot/vmp/aiot/dao/AiAlertMapper.java

@@ -15,8 +15,11 @@ public interface AiAlertMapper {
     @Options(useGeneratedKeys = true, keyProperty = "id", keyColumn = "id")
     int add(AiAlert alert);
 
+    @Select("SELECT COUNT(1) FROM wvp_ai_alert WHERE alert_id=#{alertId}")
+    int countByAlertId(@Param("alertId") String alertId);
+
     @Select("SELECT a.*, r.name AS roi_name, " +
-            "COALESCE(SUBSTRING_INDEX(sp.gb_name, '/', 1), sp.name, sp.app) AS camera_name " +
+            "COALESCE(sp.name, sp.app) AS camera_name " +
             "FROM wvp_ai_alert a " +
             "LEFT JOIN wvp_ai_roi r ON a.roi_id = r.roi_id " +
             "LEFT JOIN wvp_stream_proxy sp ON a.camera_id = sp.camera_code " +
@@ -29,7 +32,7 @@ public interface AiAlertMapper {
 
     @Select(value = {"<script>" +
             "SELECT a.*, r.name AS roi_name, " +
-            "COALESCE(SUBSTRING_INDEX(sp.gb_name, '/', 1), sp.name, sp.app) AS camera_name " +
+            "COALESCE(sp.name, sp.app) AS camera_name " +
             "FROM wvp_ai_alert a " +
             "LEFT JOIN wvp_ai_roi r ON a.roi_id = r.roi_id " +
             "LEFT JOIN wvp_stream_proxy sp ON a.camera_id = sp.camera_code " +

src/main/java/com/genersoft/iot/vmp/aiot/service/impl/AiAlertServiceImpl.java

@@ -27,9 +27,8 @@ public class AiAlertServiceImpl implements IAiAlertService {
         if (alert.getReceivedAt() == null) {
             alert.setReceivedAt(LocalDateTime.now().format(FORMATTER));
         }
-        // 防止重复插入
-        AiAlert existing = alertMapper.queryByAlertId(alert.getAlertId());
-        if (existing != null) {
+        // 防止重复插入（轻量查询，不做 JOIN）
+        if (alertMapper.countByAlertId(alert.getAlertId()) > 0) {
             log.debug("[AiAlert] 告警已存在, 跳过: alertId={}", alert.getAlertId());
             return;
         }