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

default/themed/ghostty.conf.tpl

@@ -0,0 +1,22 @@
+background = {{ background }}
+foreground = {{ foreground }}
+cursor-color = {{ cursor }}
+selection-background = {{ selection_background }}
+selection-foreground = {{ selection_foreground }}
+
+palette = 0={{ color0 }}
+palette = 1={{ color1 }}
+palette = 2={{ color2 }}
+palette = 3={{ color3 }}
+palette = 4={{ color4 }}
+palette = 5={{ color5 }}
+palette = 6={{ color6 }}
+palette = 7={{ color7 }}
+palette = 8={{ color8 }}
+palette = 9={{ color9 }}
+palette = 10={{ color10 }}
+palette = 11={{ color11 }}
+palette = 12={{ color12 }}
+palette = 13={{ color13 }}
+palette = 14={{ color14 }}
+palette = 15={{ color15 }}