docs: update feature screenshots (#1452)

Floatpane Bot and floatpanebot created 

## What?

Refreshes the feature screenshots in `docs/docs/assets/features/`.

### Screenshots included:
- `compose_email.png`
- `compose_empty.png`
- `drafts.png`
- `email_view.png`
- `inbox_view.png`
- `main_menu.png`
- `settings.png`
- `theme_settings.png`
- `threading_demo.png`

## Why?

Keeps documentation visuals aligned with the current TUI. Generated
automatically by the Generate Screenshots workflow on the latest
release.

Co-authored-by: floatpanebot <278062430+floatpanebot@users.noreply.github.com>

Change summary

docs/docs/assets/features/settings.png | 0 
1 file changed

Detailed changes