[BUG] 后台 AI 自动命名对思考型模型静默失败: max_tokens=100 被思考耗尽, 会话标题停留在首条消息占位文本中

Problem description: The background AI automatic naming (the generator that writes the `ai-title` entry during the session, as opposed to `/rename`) in the desktop client always fails silently when `models.haiku` / `models.main` is configured to be a `thinking` model. The session list title always stays at the placeholder title written in the first round (i.e. the truncated text of the first user message), and is not overwritten by the AI-generated title.