refactor: use tempfile for import/export/stats artifacts

SubMind.py

@@ -4,6 +4,7 @@ import requests
 import datetime
 import dateparser
 import logging
+import tempfile
 import pandas as pd
 import matplotlib
 import matplotlib.pyplot as plt
@@ -458,7 +459,8 @@ async def stats(update: Update, context: CallbackContext):
     ax.axis('equal')
 
     fig.tight_layout()
-    image_path = f'stats_{user_id}.png'
+    with tempfile.NamedTemporaryFile(prefix=f'stats_{user_id}_', suffix='.png', delete=False) as tmp:
+        image_path = tmp.name
     plt.savefig(image_path)
     plt.close(fig)
 
@@ -481,7 +483,9 @@ async def export_command(update: Update, context: CallbackContext):
         await update.message.reply_text("您还没有任何订阅数据，无法导出。")
         return
 
-    export_path = f'export_{user_id}.csv'
+    with tempfile.NamedTemporaryFile(prefix=f'export_{user_id}_', suffix='.csv', delete=False) as tmp:
+        export_path = tmp.name
+
     df.to_csv(export_path, index=False, encoding='utf-8-sig')
 
     try:
@@ -506,7 +510,8 @@ async def import_upload_received(update: Update, context: CallbackContext):
         return IMPORT_UPLOAD
 
     file = await update.message.document.get_file()
-    file_path = f'import_{user_id}.csv'
+    with tempfile.NamedTemporaryFile(prefix=f'import_{user_id}_', suffix='.csv', delete=False) as tmp:
+        file_path = tmp.name
     try:
         await file.download_to_drive(file_path)
         df = pd.read_csv(file_path, encoding='utf-8-sig')