Fix Chinese translations for "Activate for Duration" menu item

[PrintNow]

Chinese Translation Update

Original English: Activate for Duration
Previous Chinese: 在一段时间内启动
New Chinese: 激活时长

Context

In the app’s menu, this option lets users choose how long the app remains active (e.g., 5 minutes, 1 hour, or unlimited).

Reasoning

The previous translation “在一段时间内启动” literally means “start within a period of time,” which sounds like scheduling an activation.
However, this option defines how long the screen remains active, not when it turns on.

The updated translation “激活时长” is clearer, more natural, and better describes the intended behavior.