feat: add omarchy theme template system with management scripts

- New default/themed/ templates (alacritty, btop, foot, ghostty, helix,
  hyprland, hyprlock, kitty, mako, obsidian, rofi, swayosd, tmux,
  walker, waybar, keyboard.rgb, gum.env, etc.)
- Add omarchy-* theme management scripts (install, refresh, set, remove,
  update, bg-set, colors-from-alacritty, current, etc.)
- Add omarchy restart/hook scripts (btop, hyprctl, hypridle, mako, tmux)
- Add installer/environment.sh for shared env vars
- Add 19 theme directories with colors.toml, vscode.json, backgrounds,
  and app-specific configs (catppuccin, everforest, gruvbox, nord,
  tokyo-night, rose-pine, etc.)
- Update bing-wallpaper script to use new .config/omarchy path

installer/environment.sh

@@ -0,0 +1,6 @@
+#!/bin/sh -e
+
+mkdir -p ${HOME}/.config/environment.d
+
+${DOTFILES_DIR}/sync-config config/environment.d/
+echo "DOTFILES_DIR=${DOTFILES_DIR}" | tee -a ${HOME}/.config/environment.d/dotfiles.conf