add a screenshot to both readmes

Desktop shot at .config/rice/screenshot.webp, shown at the top of the root
README and the rice one.

Converted from the source PNG: it was 2.36 MB, and PNG recompression only got
it to 2.30 MB because the sakura wallpaper is a photo. WebP at q90 is 0.38 MB
with the terminal text still sharp at 1:1, which is worth it in a repo the
installer clones in full.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011beBgzmH72WFn8wiWqRZPf

.config/rice/README.md

@@ -2,6 +2,8 @@
 
 bspwm rice. Palette sampled from `~/.config/bspwm/wallpaper/wallpaper.jpg`.
 
+![Sakura Line - bspwm, polybar and btop over the sakura wallpaper](screenshot.webp)
+
 ## Replicate on a fresh machine
 
 ```sh
@@ -103,6 +105,7 @@ app's config.
 .config/rice/
 ├── install.sh        one-shot bootstrap
 ├── packages.txt      package list ("aur:" prefix = needs an AUR helper)
+├── screenshot.webp   the shot in this README
 ├── st/config.h       st build config
 └── particles/        wallpaper-layer particle field (source + Makefile)
 ```

README.md

@@ -3,6 +3,8 @@
 Everything needed to rebuild my Arch + bspwm desktop on a bare machine:
 **Sakura Line**, a bspwm rice with a GTK control panel and a particle wallpaper layer.
 
+![Sakura Line - bspwm, polybar and btop over the sakura wallpaper](.config/rice/screenshot.webp)
+
 ## Install
 
 ```sh