allow KeePassDX to run in the lock screen

### Checks

- [x] I have read the Wiki, searched the open issues, and still think this is a new feature.

### Explain the problem clearly and succinctly:

When logging in by reading a QR code and using a passkey the workflow is like this:

1) Start with a locked phone
2) Use shortcut (like double-tapping the power button) to launch camera
3) Read QR code
4) Unlock phone
5) Unlock vault
6) Authenticate

### Describe the solution you'd like:

One unlock that is step 4 in the aforementioned workflow could be eliminated if KeePassDX (or its relevant Activity) was able to run in the lock screen.

### Describe alternatives you've considered:

_No response_

### Additional context:

_No response_

Start by locating the relevant KeePassDX Activity and the Android lock-screen behavior involved in launching it from the camera and passkey workflow. Done means KeePassDX or that Activity can run while the phone is locked, eliminating the separate phone unlock step without changing the vault unlock and authentication steps.

Written by the indexing model from the issue text.