refactor: migrate to template-based theme system, clean up old per-theme configs

- Remove per-theme app configs (alacritty, foot, ghostty, hyprland,
  hyprlock, mako, rofi, swayosd, tmux, walker, waybar, etc.) now
  handled by default/themed/ templates
- Update omarchy scripts (bg-next, list, set) for new template flow
- Update configs: bootstrap, nvim, rofi, tmux, mako
- Tweak installers (02-install-base.sh, btop, desktop, goose, nvim,
  obsidian, theme, tmux)
- Remove obsolete hyprland-rofi-* and hyprland-walker-* scripts
- Update neovim.lua across remaining themes

installer/tmux.sh

@@ -5,9 +5,9 @@ if [[ ! -x "$(command -v tmux)" ]]; then
 fi
 
 ${DOTFILES_DIR}/sync-config config/tmux
-THEMES_DIR="${HOME}/.local/share/themes"
+THEME_DIR="${HOME}/.config/omarchy/current/theme"
 
-ln -snf ${THEMES_DIR}/current/theme/tmux ${HOME}/.config/tmux/theme
+ln -snf ${THEME_DIR}/current/theme/tmux ${HOME}/.config/tmux/theme
 
 # setup tmux
 if [[  ! -d ~/.config/tmux/plugins/tpm ]]; then