feat: Create Signed Evidence Bundles and Append-Only Transparency Log

[Mosas2000]

Area

Evidence, reports, and compliance

Problem

Report hashes and source metadata do not provide a portable, independently verifiable proof of exactly which raw observations, code/config versions, and chain evidence produced a report.

Scope

Create signed evidence bundles containing canonical inputs, Merkle commitments, finality metadata, decoder versions, query parameters, derived outputs, and signer rotation metadata. Publish an append-only transparency log with inclusion and consistency proofs.

Acceptance criteria

• A verifier can validate a bundle offline without trusting the application database.
• Any changed input or output invalidates the signature/commitment.
• Key rotation and revocation are represented in the log.
• Bundles support partial disclosure while preserving proof validity.
• REST and PDF exports link to the exact evidence root.

[nasarajoe]

may I work on this issue?

[grantfox-oss]

🦊 GrantFox — @nasarajoe has been assigned to this issue as part of the Third Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #1019)
2. Your PR will be reviewed by the StellaBridge maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Third Campaign campaign!

@nasarajoe's PR #1233 was approved and merged by @Mosas2000.

🏆 @nasarajoe: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (86 total points). Track your full progress on GrantFox.

👏 Great work, @nasarajoe! Keep contributing to StellaBridge.