Verify the complete expected marketplace release tree #517

🤖 Generated by the Agentic Engineer

Problem and evidence

Marketplace verification trusts a successful but incomplete changed-path observation when inspecting a release commit. A controlled empty observation allows the verifier to accept a real child commit that also changes unrelated tracked content. The complete native observation correctly rejects it.

Expected outcome

Verify the complete release tree against independently reconstructed expected content. Parent identity and two manifest blobs alone cannot establish that all other committed content is preserved.

Acceptance criteria

• Reproduce the incorrect VERIFIED result with a real Git child commit.
• Bind the complete tree to the expected two-manifest release change.
• Refuse omitted changes, extra tracked content and incomplete producer observations.
• Preserve valid release commits and historical read-only inspection.
• Run release verification and preparation regression suites.

Rough size: S. Part of #101.