refactor: merge _check_fault and _classify_fault into _analyze_fault

一次调用返回(fault_status, fault_type)元组，简化诊断逻辑

src/diagnose.py

@@ -65,13 +65,9 @@ class FaultDiagnoser:
                 roi = img[y1:y2, x1:x2]
                 temp_features = self.extractor.extract_from_roi(roi)
 
-                fault_status = self._check_fault(temp_features)
+                fault_status, fault_type = self._analyze_fault(temp_features)
                 temp_features['fault_status'] = fault_status
-                # abnormal 时才进行故障分类，normal 时类型为 none
-                if fault_status == 'abnormal':
-                    temp_features['fault_type'] = self._classify_fault(temp_features)
-                else:
-                    temp_features['fault_type'] = 'none'
+                temp_features['fault_type'] = fault_type
 
                 result['faults'].append(temp_features)
         else:
@@ -80,51 +76,36 @@ class FaultDiagnoser:
         result['summary'] = self._generate_summary(result['faults'])
         return result
 
-    def _check_fault(self, temp_features: Dict) -> str:
+    def _analyze_fault(self, temp_features: Dict) -> tuple:
         """
-        根据温度特征判断是否有故障
+        分析温度特征，判断故障状态和类型
 
         Args:
             temp_features: 温度特征
 
         Returns:
-            'normal' 或 'abnormal'
+            (fault_status, fault_type) 元组
         """
         max_temp = temp_features.get('temp_max', 0)
-        mean_temp = temp_features.get('temp_mean', 0)
         std_temp = temp_features.get('temp_std', 0)
+        temp_range = max_temp - temp_features.get('temp_mean', 0)
 
         max_threshold = self.temp_threshold.get('max_temp', 200)
         std_threshold = self.temp_threshold.get('std_temp', 50)
 
-        if max_temp > max_threshold or std_temp > std_threshold:
-            return 'abnormal'
-        return 'normal'
-
-    def _classify_fault(self, temp_features: Dict) -> str:
-        """
-        故障分类
-
-        Args:
-            temp_features: 温度特征
-
-        Returns:
-            故障类型
-        """
-        max_temp = temp_features.get('temp_max', 0)
-        mean_temp = temp_features.get('temp_mean', 0)
-        std_temp = temp_features.get('temp_std', 0)
-
-        temp_range = max_temp - mean_temp
+        # 判断状态：两项都不超标才为 normal
+        if max_temp <= max_threshold and std_temp <= std_threshold:
+            return ('normal', 'none')
 
+        # 分类故障类型
         if std_temp > 30:
-            return 'hotspot'
+            return ('abnormal', 'hotspot')
         elif temp_range > 50:
-            return 'local_overheating'
+            return ('abnormal', 'local_overheating')
         elif max_temp > 180:
-            return 'overheat'
+            return ('abnormal', 'overheat')
         else:
-            return 'suspect'
+            return ('abnormal', 'suspect')
 
     def _generate_summary(self, faults: List[Dict]) -> Dict:
         """