Wraps the backend in 'tmux new-session -A' with a per-backend, per-directory
session name, so agent sessions survive SSH drops and re-running the same
command reattaches. Falls back to a direct run when already inside tmux,
and errors clearly when tmux is not installed.
Hermes -r/--resume requires a session id and has no -c shorthand, so
bare 'myhermes -r' failed with an argparse error. Translate
myagents-style flags like the codex backend:
- bare -r/--resume -> 'hermes sessions browse' (interactive picker)
- -r/--resume <id> -> '--resume <id> --no-restore-cwd'
- -c/--continue/--last -> '--continue --no-restore-cwd'
--no-restore-cwd keeps resumed sessions in the launch cwd, matching
myclaude semantics instead of jumping to the session's original cwd.