fix(plymouth): recolor splash art from the palette for contrast

The shipped boot art was a fixed navy that vanished against dark theme
bases. Recolor each element from theme-state.json at build time (flat
fill, alpha preserved): foreground glyphs (logo, padlock, password dots)
→ text, the field/track boxes (entry, progress_box) → surface, and the
progress fill → accent. text/surface both contrast with base in either
polarity, so the splash now reads on light and dark themes alike.

Adds imagemagick as a build-time input to the theme derivation. Like the
background tint, this follows the theme as of the last system rebuild.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

modules/nixos/plymouth.nix

@@ -14,7 +14,16 @@ let
     if cfg.stateFile != null
     then builtins.fromJSON (builtins.readFile cfg.stateFile)
     else { };
-  base = lib.removePrefix "#" ((state.colors or { }).base or "#1a1b26");
+  colorOf = key: fallback: lib.removePrefix "#" ((state.colors or { }).${key} or fallback);
+  base = colorOf "base" "#1a1b26";
+  # Splash elements are recolored from the palette so they read on any
+  # base, light or dark: foreground glyphs → text, field/track boxes →
+  # surface (raised from base in both polarities), the progress fill →
+  # accent. The shipped art is a fixed navy that vanished on dark themes.
+  text = colorOf "text" "#a9b1d6";
+  surface = colorOf "surface" "#32344a";
+  accent = colorOf "accent" "#7aa2f7";
+  magick = lib.getExe' pkgs.imagemagick "magick";
 
   # Plymouth's Window.SetBackgroundTopColor takes three floats in
   # 0.0–1.0; the .plymouth metadata's ConsoleLogBackgroundColor takes a
@@ -36,13 +45,26 @@ let
 
     src = ./plymouth;
 
+    nativeBuildInputs = [ pkgs.imagemagick ];
+
     installPhase = ''
-      mkdir -p $out/share/plymouth/themes/nomarchy
+      themedir=$out/share/plymouth/themes/nomarchy
-      cp * $out/share/plymouth/themes/nomarchy/
+      mkdir -p "$themedir"
+      cp * "$themedir/"
+
+      # Recolor the splash art from the palette (flat fill, alpha kept) so
+      # it reads on any base instead of the shipped fixed navy.
+      recolor() { ${magick} "$themedir/$1" -fill "#$2" -colorize 100 "$themedir/$1"; }
+      recolor logo.png         ${text}     # centre monogram
+      recolor lock.png         ${text}     # password-prompt padlock
+      recolor bullet.png       ${text}     # password dots
+      recolor entry.png        ${surface}  # password field box
+      recolor progress_box.png ${surface}  # progress track
+      recolor progress_bar.png ${accent}   # progress fill
 
       # Point the .plymouth metadata into the store
-      sed -i "s|/usr/share/plymouth/themes/nomarchy|$out/share/plymouth/themes/nomarchy|g" \
+      sed -i "s|/usr/share/plymouth/themes/nomarchy|$themedir|g" \
-        $out/share/plymouth/themes/nomarchy/nomarchy.plymouth
+        "$themedir/nomarchy.plymouth"
 
       # Bake the theme's base color: RGB floats for the script's
       # Window.SetBackground* calls, 0xRRGGBB for ConsoleLogBackground.
@@ -50,9 +72,9 @@ let
         -e 's|@BG_R@|${channel 0}|g' \
         -e 's|@BG_G@|${channel 2}|g' \
         -e 's|@BG_B@|${channel 4}|g' \
-        $out/share/plymouth/themes/nomarchy/nomarchy.script
+        "$themedir/nomarchy.script"
       sed -i 's|@BG_HEX@|${base}|g' \
-        $out/share/plymouth/themes/nomarchy/nomarchy.plymouth
+        "$themedir/nomarchy.plymouth"
     '';
   };
 in