fix(new-server): rollback path is not transactional

[AbstractNucleus]

What: routes/new_server.py rollback uses shutil.rmtree(target, ignore_errors=True) plus db.delete_server(...) with no transactional guarantee.

Why: A partial failure (scaffold succeeds, DB insert fails, then rmtree fails) leaves the host in an inconsistent state with no automated recovery.

Approach: Either (a) add a reconcile task that detects orphan dirs / orphan DB rows on startup, or (b) at minimum, log and surface the failed cleanup path so an operator can act.

[AbstractNucleus]

This was generated by AI during triage.

Routed to ready-for-human — picking the recovery shape is a design call:

• Option A: a startup reconcile task that scans for orphan dirs / orphan DB rows.
• Option B: surface the failed cleanup path to the operator and rely on manual recovery.

Either is defensible; the choice depends on how much background autonomy we want and on the tolerance for orphan state. Better made by a human before drafting an agent brief.