[CT-19] Build batch document verification contract

[mftee]

Problem

When a shipment is completed, multiple documents (Bill of Lading, Proof of Delivery, Customs Declaration) need to be verified against their on-chain hashes simultaneously. The current document contract requires one transaction per document, making post-completion verification slow and expensive.

Proposed Solution

Create a batch verification function inside contracts/package/document-verification/ that verifies multiple submitted hashes against their registered on-chain values in a single transaction.

Note: All work must be done inside the contracts/package/ directory. Do not modify any existing contract files outside this folder.

Acceptance Criteria

• verify_documents_batch(doc_ids: Vec<BytesN<32>>, submitted_hashes: Vec<BytesN<32>>) function
• Input vectors must have equal length; mismatched lengths return InputLengthMismatch
• Returns Vec<VerificationResult> where VerificationResult = { doc_id: BytesN<32>, matches: bool, stored_hash: BytesN<32> }
• A mismatch on one document does NOT halt verification of the remaining documents (all are processed independently)
• The response also includes a summary: { total: u32, matched: u32, mismatched: u32 }
• Unit tests cover: all hashes match, partial match (2 of 3), all mismatch, empty input (returns empty result)

[brite-side0]

@brite-side0 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Please allow me to work on this issue with you.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @brite-side0 to this issue.

[phertyameen]

@phertyameen has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

I’d like to work on this issue. I have experience with Soroban smart contracts, testing, and secure contract design, and I can implement the required functionality with clean, maintainable code and comprehensive test coverage.

I’ll follow the project requirements closely, keep changes scoped to the specified files/directories, and ensure the solution is reliable and CI-friendly.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @phertyameen to this issue.

[drips-wave]

Congratulations, @phertyameen! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @phertyameen: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

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