Sakura Line: retheme the whole desktop from the wallpaper

Palette sampled from bspwm/wallpaper/wallpaper.jpg and applied per-role
(not per-hex, so terminal green stays green and nvim's LineNr/Comment
stay recessive) across st, kitty, polybar, rofi, dunst, nvim, qt5ct/qt6ct
and GTK 2/3/4.

Also:
- rofi drun centred, icons enabled
- polybar translucent (true ARGB) and rounded; picom corner-radius, with
  the desktop layer and fullscreen windows excluded
- fix qt5ct color_scheme_path pointing at a nonexistent /home/carrie
- export QT_QPA_PLATFORMTHEME so qt6ct is actually consulted
- point GTK at an icon theme that exists on this system
- add .config/rice: one-shot install.sh (--dry-run supported), package
  list, vendored st config.h (gitignored upstream) and the particles
  wallpaper-layer source, so a clone reproduces the rice

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Cn3dHfbgNYdbZvzb1b3GQt

.config/btop/themes/sakura-line.theme

@@ -0,0 +1,53 @@
+# btop - Sakura Line, sampled from bspwm/wallpaper/wallpaper.jpg
+theme[main_bg]=""
+theme[main_fg]="#e9eefb"
+theme[title]="#e9eefb"
+theme[hi_fg]="#92b9ea"
+theme[selected_bg]="#2e2842"
+theme[selected_fg]="#92b9ea"
+theme[inactive_fg]="#7f7796"
+theme[graph_text]="#c9d1e2"
+theme[meter_bg]="#201b30"
+theme[proc_misc]="#8ab6c4"
+
+theme[cpu_box]="#3d3752"
+theme[mem_box]="#3d3752"
+theme[net_box]="#3d3752"
+theme[proc_box]="#3d3752"
+theme[div_line]="#3d3752"
+
+theme[temp_start]="#8fae74"
+theme[temp_mid]="#d8a87c"
+theme[temp_end]="#cf6a80"
+
+theme[cpu_start]="#7c9ede"
+theme[cpu_mid]="#92b9ea"
+theme[cpu_end]="#d0a4d8"
+
+theme[free_start]="#4a5a6e"
+theme[free_mid]="#7fa3ad"
+theme[free_end]="#a3c0cb"
+
+theme[cached_start]="#6f8fc4"
+theme[cached_mid]="#92b9ea"
+theme[cached_end]="#aecdf5"
+
+theme[available_start]="#8a6a52"
+theme[available_mid]="#d8a87c"
+theme[available_end]="#e9c79b"
+
+theme[used_start]="#7a4256"
+theme[used_mid]="#cf6a80"
+theme[used_end]="#e0798f"
+
+theme[download_start]="#5f6f9e"
+theme[download_mid]="#7c9ede"
+theme[download_end]="#92b9ea"
+
+theme[upload_start]="#7a4a7e"
+theme[upload_mid]="#b483c0"
+theme[upload_end]="#d0a4d8"
+
+theme[process_start]="#8fae74"
+theme[process_mid]="#a8c68d"
+theme[process_end]="#e9c79b"