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/nvim/lua/config/highlights.lua

@@ -1,8 +1,8 @@
 -- Force LazyVim UI elements to use Carrie's green 🐾🌿
 
-local green = "#afb979"
-local green_bright = "#cbd88c"
-local bg = "#141414"
+local green = "#8fae74"
+local green_bright = "#a8c68d"
+local bg = "#0f0d17"
 
 local function hi(group, opts)
   vim.api.nvim_set_hl(0, group, opts)
@@ -29,7 +29,7 @@ hi("CmpNormal", { bg = bg })
 -- ✅ Telescope menus (if you use it)
 hi("TelescopeBorder", { fg = green })
 hi("TelescopePromptBorder", { fg = green })
-hi("TelescopeSelection", { bg = "#303030" })
+hi("TelescopeSelection", { bg = "#2e2842" })
 hi("TelescopePromptPrefix", { fg = green_bright })
 
 -- ✅ Floating menus in general