fix(worker): 修复 dedup fingerprint JSON 序列化失败 - np.float32 转原生 float

根因：cv2.normalize() 返回 np.float32 数组，color_histograms 直接存进 dict 后
SQLAlchemy JSON 序列化时报 'float32 is not JSON serializable'

修复：VideoFingerprint.to_dict() 中统一转 Python 原生类型
- color_histograms: np.float32 → float
- duration: 统一转 float
- resolution: np.int32 → int

apps/worker/video_processing/dedup.py

@@ -93,12 +93,16 @@ class VideoFingerprint:
     resolution: tuple[int, int]
 
     def to_dict(self) -> dict:
+        # 注意：color_histograms 里的值可能是 np.float32（来自 cv2.normalize），
+        # 直接存进 dict 后 SQLAlchemy JSON 序列化会报 "float32 is not JSON serializable"。
+        # 这里统一转成 Python 原生 float。
+        native_histograms = [[float(v) for v in hist] for hist in self.color_histograms]
         return {
             "md5": self.md5,
             "keyframe_phashes": self.keyframe_phashes,
-            "color_histograms": self.color_histograms,
-            "duration": self.duration,
-            "resolution": list(self.resolution),
+            "color_histograms": native_histograms,
+            "duration": float(self.duration),
+            "resolution": [int(self.resolution[0]), int(self.resolution[1])],
         }