LockScreen password UX.

### Feature Description

LockScreen password-input keybind overview for learning/remembering the current emacs binds.

### Use Case

- clearing long misspelled passwords quickly
- not having to remember a programs specific bind, or at least being able to view the keybinds where I currently need them.
- making DMS more accessible to new users.

### Compositor(s)

All compositors

### If Other, please specify

_No response_

### Proposed Solution

E.g. A button labelled `ctrl+?`, `ctrl+/` or something similar. That opens a keybinds overview when clicked or when the shortcut on the label is pressed.

### Alternatives/Existing Solutions

I think most password inputs in GUI's don't use emacs shortcuts and allow text selection.
E.g. the usual `ctrl+a` -> delete flow.

My preferred way of interacting with password inputs is the text-selection flow, since it is most common.
But I think this will make some users unhappy if emacs binds were removed.

Maybe both could be supported but that would be a lot of extra work.

An overview of current keybinds would be easiest I believe.

Start by locating the LockScreen password input and its existing Emacs keybind handling. Review how the password field is presented across compositors, then determine how the proposed keybind overview should be opened; done means users can discover the current binds from the password screen without losing existing behavior.

Written by the indexing model from the issue text.