No way to enforce the app screen lock

### Steps to reproduce

1. Enable screen lock
2. Lock the phone using power button
3. Unlock the phone within a short period

### Outcome

#### What did you expect?
Element X is locked

#### What happened instead?
Element X is unlocked

Basically, there's no way to ensure the app is locked, other than waiting the timeout (which is unknown and not configurable)

### Your phone model

_No response_

### Operating system version

_No response_

### Application version and app store

26.09.1

### Homeserver

_No response_

### Will you send logs?

No

### Will you submit a Pull Request?

No

No file or test entry point is named. Start by reproducing the behavior in Element X Android 26.09.1 with screen lock enabled, then locate the app's screen-lock handling and existing tests. Done means the app can be reliably forced to lock when the phone is locked and the short-unlock behavior is covered.

Written by the indexing model from the issue text.