herdr-estate v0.2.3

- The picker run from a pane's shell now hands a row for its own
  workspace to herdr, as the popup does, reading the workspace from
  `$HERDR_WORKSPACE_ID`. v0.2.2's Ctrl-f fix held only in the popup.
- A `prepare` step that touches the terminal, such as
  `stty -echo </dev/tty`, now fails at once instead of sitting stopped
  until the 60-second timeout. `prepare` keeps its own process group and
  drops the terminal. It stays in the verb's session, so herdr closing
  the pane, popup or workspace still ends it.
- A failed `prepare` that left a process holding its output open is
  refused with what it wrote, not only its exit status.