v1.38.1

fix(ws): list coders that worktree layouts start, not just ones typed into a shell

A coder started by a worktree layout was missing from the dashboard's AGENTS
section, so a worktree running two agents showed only one. Layouts launch the
coder as zsh -c '<coder>', which makes tmux report the pane's program as
zsh for the coder's whole life, and the "pane is back to a plain shell" check
treated it as a coder that had exited.

• The shell check now applies only to a pane that falls back to a shell when its
  program exits: one started as tmux's default shell, the shell by name or
  $SHELL, or a command that ends by exec'ing a shell (<coder>; exec zsh,
  tmux-resurrect's restored panes). Any other pane closes when its command
  exits, so a shell there is only the wrapper around a running coder.
• The dashboard's 3-second tmux scan reads each pane's start command for this,
  still in its one existing tmux call.

Full Changelog: v1.38.0...v1.38.1