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/rice/packages.txt

@@ -0,0 +1,54 @@
+# Sakura Line rice - Arch package list.
+# Lines starting with # are ignored. "aur:" prefix needs an AUR helper.
+
+# --- window manager / desktop ---
+bspwm
+sxhkd
+polybar
+picom
+rofi
+dunst
+feh
+xdotool
+xorg-xrandr
+xorg-xprop
+
+# --- build toolchain (st + particles) ---
+base-devel
+git
+pkgconf
+libx11
+libxext
+libxft
+libxrandr
+libxfixes
+libxinerama
+cairo
+harfbuzz
+fontconfig
+freetype2
+gd
+
+# --- fonts ---
+ttf-jetbrains-mono-nerd
+noto-fonts
+noto-fonts-emoji
+
+# --- theming ---
+qt6ct
+papirus-icon-theme
+aur:bibata-cursor-theme
+
+# --- apps ---
+thunar
+fastfetch
+
+# --- showcase toys ---
+cava
+btop
+cmatrix
+asciiquarium
+onefetch
+aur:cbonsai
+aur:pipes.sh
+aur:tty-clock