fix: model过滤后为空时退回到不过滤，避免单模型ppid定价变空

pricing/pricing.py

@@ -920,19 +920,19 @@ async def get_pricing_display(ppid, model=None):
 			items.append(item)
 
 	# 按模型过滤：只返回匹配该模型的定价项
+	# 如果过滤后为空（单模型ppid没有model字段），退回不过滤
 	if model:
 		filtered_items = []
 		for item in items:
 			item_model = None
-			# 从 filters dict 中取 model
 			if item.get('filters') and isinstance(item['filters'], dict):
 				item_model = item['filters'].get('model')
-			# 从 filter_labels 中取（用 key 名"模型"查找）
 			if not item_model and item.get('filter_labels'):
 				item_model = item['filter_labels'].get('模型')
 			if item_model == model:
 				filtered_items.append(item)
-		items = filtered_items
+		if filtered_items:
+			items = filtered_items
 
 	# 生成可读价格表
 	display_lines = [f"【{getattr(r, 'name', '')}】定价:"]