fix: standardize UTC timestamp handling

app/prediction.py

@@ -4,7 +4,6 @@ import logging
 import os
 import uuid
 from dataclasses import dataclass
-from datetime import datetime
 from pathlib import Path
 from typing import Any
 
@@ -20,6 +19,7 @@ from werkzeug.datastructures import FileStorage
 from werkzeug.utils import secure_filename
 
 from .config import IMAGE_DIR, UPLOAD_DIR
+from .time_utils import utc_now
 
 CHINESE_FONT_CANDIDATES = [
     "Noto Sans CJK SC",
@@ -386,7 +386,7 @@ def run_prediction(uploaded: FileStorage, user_id: int, model) -> PredictionArti
     if not original_filename:
         raise PredictionError("未选择文件")
 
-    timestamp = datetime.now().strftime("%Y%m%d%H%M%S")
+    timestamp = utc_now().strftime("%Y%m%d%H%M%S")
     run_id = f"{timestamp}_{uuid.uuid4().hex[:8]}"
     saved_filename, suffix = secure_upload_name(original_filename, run_id)