[Feature/Improvement] Show/Hide Completed Timers

### Checklist

- [x] I made sure that the issue I am raising doesn't already exist

### Use case / Problem

Once #294 is completed, timers marked completed will still show and be available in the home screen. Some users may want to hide or sort these completed timers.

### Proposal / Solution

Add a setting to hide any timers marked as completed.

This could be implemented as a toggle button located on the appbar. Toggling it would show/hide completed timers from the list.

It may also make sense to add a sort feature, such as putting completed timers at the bottom of the list, or putting them in a different section of the list.

A possible solution could be to present the user with a dropdown setting with the following options:
- Hide completed timers
- Show completed timers
- Send completed timers to bottom

### Example Code

_No response_

### Platform

_No response_

### Audio Files/URLs/Sources

_No response_

### Mockups

_No response_

### Related issues / more information

Depends on #294.

Potentially relates to #280 as the option could be added to the settings page.

### Working on PR

yep