Remove tmux-workspaces in favor of tmuxinator-only workflow

- Delete tmux-workspaces.zsh and .tmux-templates directory
- Remove TW_* config settings from dotfiles.conf
- Clean up tmuxinator.zsh (remove import/integration code)
- Update README, INSTALL, and REFERENCE docs
- Fix editor config: .zshrc now uses DEFAULT_EDITOR from dotfiles.conf

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

INSTALL.md

@@ -259,20 +259,6 @@ MOTD_STYLE="mini"
 
 Add `.zsh` files to `~/.dotfiles/zsh/functions/` – they're auto-loaded.
 
-### Custom Tmux Templates
-
-Add templates to `~/.dotfiles/.tmux-templates/`:
-
-```bash
-# ~/.dotfiles/.tmux-templates/mytemplate.tmux
-# My custom layout
-split-window -h -p 40
-split-window -v -p 30
-select-pane -t 0
-```
-
-Use with: `tw-create myproject mytemplate`
-
 ### Custom Bookmarks
 
 ```bash