Fix LQIP manual queue run not showing loading screen and being uncancellable

[AsFLY-902]

Description:

When clicking "Run Queue Manually" for LQIP, it processes the entire queue in a single request without showing the loading screen or cancel option. This is different from how UCSS, CCSS, and VPI work; those show an "X files left in queue" screen with a Cancel link between each batch.

Because everything runs in one PHP request, the user can not cancel it. Even closing the browser tab does not stop it. The server-side process keeps running until the queue is fully cleared, the service quota runs out, or some other server/network error interrupts it. This can cause unnecessary server load, especially with larger queues.

Changes:

• Added GUI::print_loading() and Router::self_redirect() after each LQIP request in cron(), so it follows the same redirect-loop pattern as UCSS/CCSS/VPI
• Fixed the button label from "Run Queue Manually" to "Run LQIP Queue Manually" to stay consistent with the other services