🎨 优化上游ai兼容性，修复newapi返回token为空的问题

server/model/app/response/ai_claude.go

@@ -10,6 +10,8 @@ type ClaudeMessageResponse struct {
 	StopReason   string               `json:"stop_reason,omitempty"` // end_turn, max_tokens, stop_sequence
 	StopSequence string               `json:"stop_sequence,omitempty"`
 	Usage        ClaudeUsage          `json:"usage"`
+	// 统一格式的用量统计（与 OpenAI chat.completions 对齐）
+	StandardUsage *ChatCompletionUsage `json:"standard_usage,omitempty"`
 }
 
 type ClaudeContentBlock struct {