Add clear_service_metadata to remove a service's description and owner

[mikewheeleer]

Implement metadata removal for retired services

Description

set_service_metadata in contracts/escrow/src/lib.rs can write or overwrite a ServiceMetadata entry, and get_service_metadata returns Option<ServiceMetadata>, but there is no way to clear an entry once written. When a service is retired with unregister_service, its description and owner linger under DataKey::ServiceMetadata, paying ledger rent and showing up as a phantom owner in dashboards. This issue adds an explicit metadata-removal entrypoint so a retirement can be clean.

Requirements and context

• Repository scope: Agentpay-Org/Agentpay-contracts only.
• Add clear_service_metadata(env, service_id): admin-gated via the existing pattern, calling remove(&DataKey::ServiceMetadata(service_id)). Idempotent — clearing an absent entry is a no-op.
• After clearing, get_service_metadata must read back as None, matching the never-set state.
• Emit a meta_clear(service_id) event (additive) so indexers can prune their view.
• Document the relationship with unregister_service (registration and metadata are independent slots; clearing one does not touch the other).

Suggested execution

• Fork the repo and create a branch
• git checkout -b enhancement/contracts-clear-service-metadata
• Implement changes
  • Write code in: contracts/escrow/src/lib.rs — clear_service_metadata entrypoint + event.
  • Write comprehensive tests in: contracts/escrow/src/test.rs — set then clear returns None; clear on never-set is a no-op; registration flag untouched; non-admin caller panics.
  • Add documentation: clarify metadata vs. registration lifecycle in README.md.
  • Include NatSpec-style doc comments (///) matching the existing style in lib.rs.
  • Validate security: only admin can clear, no accidental registration removal.
• Test and commit

Test and commit

• Run cargo fmt --all -- --check, cargo build, and cargo test.
• Cover edge cases: clear then re-set, clear after unregister, usage history preserved.
• Include the full cargo test output and a short security notes section in the PR description.

Example commit message

feat: add clear_service_metadata for clean service retirement

Guidelines

• Minimum 95 percent test coverage for impacted modules.
• Clear, reviewer-focused documentation.
• Timeframe: 96 hours.

Community & contribution rewards

• 💬 Join the AgentPay community on Discord for questions, reviews, and faster merges: https://discord.gg/eXvRKkgcv
• ⭐ This is a GrantFox OSS / Official Campaign task and may be rewarded. When your PR is merged you'll be prompted to rate the project — if this issue and the maintainers helped you ship, we'd be grateful for a 5-star rating. Clear questions in Discord and tidy, well-tested PRs are the fastest path to a merge and a reward.

[Jagadeeshftw]

Hi, I’d love to take on this issue! With my expertise in Rust, Stellar, and smart contract development, I can implement a clean and efficient solution.

🚀 Why Me?

• Proven Blockchain Experience – Hands-on work with Stellar, Solidity, and Rust, building secure and optimized smart contracts.
• Open Source Contributor – Actively contributed to 50+ open-source projects, showcasing adaptability and collaboration.
• Efficient & Reliable – I deliver high-quality, production-ready solutions quickly, ensuring security and scalability.

⏱ Timeline

I estimate completing this within 24 hours. Let me know if I can proceed!

[grantfox-oss]

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

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #39)
2. Your PR will be reviewed by the Agentpay-Org maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

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

@Jagadeeshftw's PR #49 was approved and merged by @mikewheeleer.

🏆 @Jagadeeshftw: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (433 total points). Track your full progress on GrantFox.

👏 Great work, @Jagadeeshftw! Keep contributing to Agentpay-Org.