Feature Request: Auto-lock timeout option & FaceID for Screen Lock settings

### Your use case

As a user who frequently switches between Element and other apps while on the go, the current screen lock behavior is cumbersome. Every time I navigate back to Element, I have to trigger FaceID, which slows down my workflow significantly.

Additionally, when accessing Screen Lock settings, I'm required to enter a PIN even though FaceID is available and configured on my device (iPhone and iPad).

### What I would like

1. **Auto-lock timeout option**: Allow users to set a timeout period (e.g., 30 seconds, 1 minute, 5 minutes) before the screen lock activates. This would let users quickly switch between apps without constantly re-authenticating.

2. **FaceID for Screen Lock settings**: When FaceID is enabled for the app, use it for authenticating Screen Lock settings changes instead of requiring the PIN.

### Have you considered any alternatives?

- Disabling screen lock entirely (not ideal for security)
- Keeping screen lock but accepting the constant FaceID prompts (current suboptimal experience)

### Additional context

This affects both iOS and iPadOS versions of Element. The current behavior makes multitasking frustrating when Element is part of the app rotation.

Start by locating the iOS and iPadOS Screen Lock settings and the existing FaceID authentication flow. Check how app switching currently triggers the lock, then define and test the requested timeout choices and FaceID-based settings authentication; done means both requested behaviors work without weakening screen-lock protection.

Written by the indexing model from the issue text.