spawnRun adopted any existing `ccam-lane-<id>` tmux session without looking
at it, so a Resume issued while the session sat at a bare shell prompt (left
by `ccam lanes shell`, or by a `claude` that had already exited) dropped the
whole argv: no `--resume` ran, no initial prompt was typed, and the API still
answered 200. The lane's DB `run_id` is not set in that case, so the ERUNLIVE
guard in the start route never saw it either.
Reuse the pane instead of erroring: when the session exists and
`#{pane_current_command}` is a shell, type the argv into that pane and record
the run. A pane running a program (a live `claude`, an editor, a build) is
still adopted untouched, so attaching shows what is running rather than typing
over it. `sendCommand` POSIX single-quotes every argument and uses
`send-keys -l`, the only place in tmux.js that composes a command line.
nntrivi2001