Persistent Exit Option During Interventions

Summary: Add an explicit, persistent exit button to reduce exit friction during intervention screens at all times.

Problem: Users currently have to perform a gesture (such as swiping up) to quit an mid-intervention, which requires extra effort compared to a simple button press. During longer interventions, the lack of an immediate, visible exit action makes users default to passively waiting out the timer.

Proposed Solution: Make the quit button on the intervention screen always-on such that it allows an immediate exit at any point without relying on the cooldown.