Rust SDK: test coverage for admin.compliance.generate_report(period) / list_reports(period, limit, offset)

[Mac-5]

Description
Add focused unit tests for admin.compliance.generate_report and admin.compliance.list_reports (implemented in Issue #122) using a mocked HTTP transport — no live server, no database.

Scope guardrail: this PR must only touch files under sdks/rust/. Do not touch anything under src/ — read the handler referenced below only to learn the request/response contract.

Requirements and context

• Cover the happy path for both methods.
• Test the documented edge case: an invalid period in generate_report must surface as a typed error distinct from a network/transport error.
• Test that the admin key (not the public key) is sent on both requests.
• Depends on Issue Transaction Export Integration Tests #122.

Suggested execution

1. Fork the repo and create a branch
   git checkout -b feature/rust-sdk-test-coverage-for-admincompliancereports
2. Implement changes
   • Set up a mocked HTTP transport returning canned responses.
   • Write happy-path tests for generate and list.
   • Write the invalid-period error-path test for generate_report.
   • Confirm cargo test is green with no network access required.
3. Test and commit
   • Run the crate's test command and confirm it's green
   • Example commit message: test(sdk): add coverage for admin compliance methods

Guidelines

• Assignment required before starting
• PR description must include: Closes #123
• PR must only touch files under sdks/rust/
• Complexity: High (200 points) — Every issue in this Wave is tagged High — full points regardless of individual scope.

[Killerjunior]

Hi maintainer, I have read and understood the issue requirements and checked the necessary documentation. I’m confident I can work on this task effectively and deliver a proper solution.