Feature: Calm Mode

### Problem I have

There's a lot of visual noise shown by default on the timeline/home feed. This can compound fatigue and/or overstimulation, as everything competes for attention and importance.

### Solution I'd like

A 'calm' mode for the timeline that reduces the amount of visual/icon noise. I suspect a lot of people would appreciate the option.

### Alternatives considered

Currently I mostly achieve this with uBlock Origin cosmetic filters. I hide the following elements:

```
! The pill button thing that shows up on your timeline when you've scrolled and there are new posts.
phanpy.social##.shiny-pill.updates-button

! Notifications bell/button on the top right of the timeline
phanpy.social##.notifications-button.plain.button

! Time next to every post on your timeline
phanpy.social##.time

! Boost/Rocket icon in the carousel
phanpy.social##.timeline-item-alt.status-carousel-link > .status-reblog > .status-pre-meta > .icon

! Notifications button from the left menu. All you need is the mentions button.
phanpy.social##[href="#/notifications"]

! Favorite count
phanpy.social##.favourite-button > small:nth-child(2)

! Boost count
phanpy.social##.reblog-button > small:nth-child(2)

! Follows on profiles
phanpy.social##.stats

! Time next to a filtered post on your timeline
phanpy.social##.status-link.timeline-item article.status.filtered span.status-filtered-info span.status-filtered-info-1 time
```

Here's a screen recording showing it being toggled on and off. The difference is subtle but immediately noticeable. Please make sure to watch the video in fullscreen:

https://github.com/user-attachments/assets/005cc9e8-bf78-4f68-a3ff-326f93f6458c

### Other

_No response_