refactor(tmux): simplify plugin list, cleanup theme template, fix installer path

- Comment out opencode/lazygit keybinds, add C-x break-pane bind
- Remove tmux-sensible and tmux.nvim plugins, add usage comments for
  remaining plugins
- Move source-file theme after tpm init
- Simplify status bar styling in themed template, drop align=centre
- Fix theme symlink path in installer (extra current/ segment)

installer/tmux.sh

@@ -7,7 +7,7 @@ fi
 ${DOTFILES_DIR}/sync-config config/tmux
 THEME_DIR="${HOME}/.config/omarchy/current/theme"
 
-ln -snf ${THEME_DIR}/current/theme/tmux ${HOME}/.config/tmux/theme
+ln -snf ${THEME_DIR}/tmux ${HOME}/.config/tmux/theme
 
 # setup tmux
 if [[  ! -d ~/.config/tmux/plugins/tpm ]]; then