feat(core): seal productive tombstones safely

[jerelvelarde]

Summary

• seal captured absence as durable Tombstones and supported-kind replacement as Tombstone plus new Object ID
• preserve same-path/same-kind logical identity for atomic-save workflows while versioning byte or executable-fidelity changes
• refuse ignore, nested-boundary, or unsupported-node scope hiding before journal mutation
• preserve legacy journal digest compatibility and crash convergence across every persistence checkpoint

Verification

• independent exact-head review: GO, P0/P1/P2 = 0/0/0
• public seal integration: 12/12
• seal unit/recovery/threat: 22/22
• full locked workspace/all-features suite green
• clippy -D warnings, macOS/Linux/Windows compile gates, packaging and public-eclipse gates green

Boundary

ADR-0005 remains Proposed. This does not claim explicit App deletion-event intake, cross-path moves, restore, Remote Head, sync, sharing, or Cloud.