dsh-shelf v0.6.0 - health check + rescue for un-resumable sessions
New:
- verify: per-session health check - orphan tool calls (#1959/#2034 family), missing turn/end, header-only, unreadable; exits 1 when unhealthy (CI-friendly), --json for machines.
- rescue : export the content of a session even when it is permanently un-resumable (plain + zstd).
Tests: 14/14 (orphan detection + rescue regression). CLI smoke on a real orphan-tool-call fixture.