Independent timestamp proofs per version

Each register version's digest, proof status, and canonical publication status. The mutually exclusive slot_capture_queue, stamping_queue, and confirmation_queue identify the exact next operation; status is capture_required, stamping_required, confirmations_pending, or current, and pipeline_invariant states and checks that ordering. Version 0.27.0 is explicitly status unreconstructable with the historical-membership reason. stamped_at and confirmed_at are separate immutable server receipts; block_time is derived from independently checkable bitcoin_info. A moderation hold makes canonical_url null without changing the frozen digest or existing proof.