fix: VLM降级跳过时不再自动标记告警为误报

VLM调用失败(skipped=true)和VLM判定误报是两种情况，
降级跳过时保留告警原始状态，让人工处理。

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

app/services/notify_dispatch.py

@@ -57,12 +57,17 @@ async def process_alarm_notification(alarm_data: Dict):
         # 写入 alarm_llm_analysis 表（复用已有表）
         _save_vlm_result(alarm_id, vlm_result)
 
-        # VLM 判定为误报 → 更新告警状态，不通知
-        if not vlm_result.get("confirmed", True):
+        # VLM 明确判定为误报（非降级跳过）→ 更新告警状态，不通知
+        if not vlm_result.get("confirmed", True) and not vlm_result.get("skipped"):
             _mark_false_alarm(alarm_id)
             logger.info(f"VLM 判定误报，跳过通知: {alarm_id}")
             return
 
+        # VLM 跳过（降级）且 confirmed=False → 不改告警状态，仅跳过通知
+        if not vlm_result.get("confirmed", True) and vlm_result.get("skipped"):
+            logger.info(f"VLM 降级跳过，不推送但保留告警状态: {alarm_id}")
+            return
+
         # ========== 2. 查表获取通知人员 ==========
         description = vlm_result.get("description", "")
         area_name, persons = _get_notify_persons(device_id, alarm_level)