compass story: add a 'done' verb to close a story

compass task exposes new, start, done, and move, but compass story only exposes new, status, and tasks. There is no compass story done. Closing a story today is a manual edit: flip the State row in the story's * Status table to DONE, set Now/Waiting on/Next to "Nothing.", bump Last touched, and (if the workflow wants it) stamp the journal. This is exactly the kind of bookkeeping the task done verb already automates one level down.

Add compass story done <story> mirroring task done:

• flip the story's * Status State to DONE (and the #+todo: keyword if it lives in frontmatter);
• normalise Now / Waiting on / Next to "Nothing." and stamp Last touched;
• guard: refuse (or warn) if any child task is still open — i.e. not in DONE / ABANDONED / moved out — so a story cannot be closed with live tasks under it;
• stamp the per-worktree journal, as task done does.

Story close-out is currently hand-done and therefore easy to get subtly wrong (a forgotten Last touched, a Now left stale, a child task quietly still BACKLOG). The asymmetry with task done is a small but real DX gap: the lifecycle verb exists for tasks and for PRs (pr merge) but stops short of the story. The guard on open child tasks is the part that earns its keep — it turns "did I close everything under this?" from a manual audit into a tool invariant.

Surfaced while closing story 812403BE (Create MASD model catalogues and org-mode variability profiles), where the close had to be done by hand.

• projects/ores.compass/ — the compass CLI implementing task done; story subcommands are defined alongside it.