feat(contracts): batch doc verification, certification registry, and lifecycle integration tests

[phertyameen]

Summary

Three new additions to contracts/package/ - no existing contract files modified.

Changes

• CT-19 document-verification/: verify_documents_batch verifies multiple doc hashes in one transaction; returns per-doc results and a matched/mismatched summary
• CT-18 certification-registry/: admin-controlled on-chain cert registry for carriers; supports registration, public verification, and revocation across 5 cert types; expired certs auto-invalidate
• CT-17 tests/integration/lifecycle.rs: end-to-end flows covering happy path, dispute + refund, and cancellation - each deploys fresh contract instances and a mock SEP-41 token

Testing

cargo test --manifest-path contracts/package/document-verification/Cargo.toml
cargo test --manifest-path contracts/package/certification-registry/Cargo.toml
cargo test --manifest-path contracts/package/tests/integration/Cargo.toml

Closes #925,
Closes #926,
Closes #927

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[mftee]

Perfect implementation