refactor: decouple TempFeatureExtractor from detection logic

- Remove detect_and_extract() method from TempFeatureExtractor
  (moved to FaultDiagnoser pipeline)
- Remove YOLO model loading from TempFeatureExtractor.__init__
- Remove duplicate train_yolo_model/validate_model from detect.py
  (already exist in scripts/train.py)
- Fix usage_example.py to use new import path and TempFeatureExtractor API

scripts/usage_example.py

@@ -8,9 +8,7 @@ from pathlib import Path
 # 添加项目根目录到路径
 sys.path.insert(0, str(Path(__file__).parent.parent))
 
-from src.detect import InfraredDetector
-from src.extract_temp import TempFeatureExtractor
-from src.diagnose import FaultDiagnoser
+from src.infrared_data import InfraredDetector, TempFeatureExtractor, FaultDiagnoser
 import cv2
 import json
 
@@ -48,7 +46,7 @@ def example3_temperature_extraction():
     """示例3：温度特征提取"""
     print("\n【示例3】温度特征提取")
 
-    extractor = TempFeatureExtractor("weights/best.pt")
+    extractor = TempFeatureExtractor()
     detector = InfraredDetector("weights/best.pt")
 
     # 读取图像