home: centralize theme and make home-manager feature-aware

- add home/theme.nix as the single Silicon Volt palette and pass it to
  home modules via extraSpecialArgs
- drive foot, hyprland, hyprlock, mako, fzf, starship, rofi and the
  herdr picker from that palette; raw config files use @color@ tokens
  substituted at build time
- pass my = config.my into home-manager; add my.pi.enable, my.flakeDir
- gate home/pi.nix on my.pi.enable (enabled on hades)
- route zshconf/hyprconf aliases and FLAKE_CONFIG through my.flakeDir
- rename the hyprland monitor option volt.monitors -> hypr.monitors
- fix use_auto_tmux command-substitution bug in zsh/init.zsh
- track home/nvim/config/lazy-lock.json for reproducible plugins
- document theming and toggles in the README

home/rofi.nix

@@ -1,16 +1,55 @@
-{ pkgs, ... }:
+{
+  pkgs,
+  lib,
+  theme,
+  ...
+}:
 
 let
   # Rofi script-mode indexer: exposes every executable user script
   # (shell, python, whatever) so the launcher finds "everything".
   rofiScripts = pkgs.writeShellScriptBin "rofi-scripts" (builtins.readFile ./rofi/rofi-scripts.sh);
+
+  # Inject the shared palette into the rasi theme (see home/theme.nix).
+  # `/. +` turns the generated derivation into a path, which the rofi module
+  # treats as a theme file to link into its data directory.
+  rofiThemeText = pkgs.writeText "volt.rasi" (
+    lib.replaceStrings
+      [
+        "@bg0@"
+        "@bg1@"
+        "@fg0@"
+        "@fg1@"
+        "@fg2@"
+        "@volt@"
+        "@voltDim@"
+        "@coral@"
+        "@border0@"
+      ]
+      [
+        "${theme.colors.bgSecondary}f2"
+        "${theme.colors.glassBg}f2"
+        theme.colors.textSecondary
+        theme.colors.textPrimary
+        theme.colors.textMuted
+        theme.colors.accentVolt
+        "${theme.colors.accentVolt}1a"
+        theme.colors.accentCoral
+        "${theme.colors.textPrimary}14"
+      ]
+      (builtins.readFile ./rofi/volt.rasi)
+  );
 in
 {
+  # Install the generated theme under the rofi theme search path and select
+  # it by name (passing a derivation directly is treated as a rasi attrset).
+  xdg.dataFile."rofi/themes/volt.rasi".source = rofiThemeText;
+
   programs.rofi = {
     enable = true;
     terminal = "${pkgs.foot}/bin/foot";
     cycle = true;
-    theme = ./rofi/volt.rasi;
+    theme = "volt";
 
     extraConfig = {
       # Combi mode searches .desktop apps (drun), binaries (run),