CDN-365: The Snapshot Diff Certificate

CDN-365 certifies the difference between the CDN-362 post-update claim register and the CDN-364 canonical state snapshot. It compares claim rows by deterministic ID alignment, records unchanged rows, retains no-op audit events, and requires every state delta to cite an accepted event pointer. The artifact demonstrates that the only state change is boundary c0 moving from active closure to active ambiguity through the accepted CDN-363 rollback challenge, with zero unbacked deltas.