Vault: emit metadata_removed event and add remove_metadata for offering cleanup

[greatest0fallt1me]

Description

CalloraVault supports set_metadata/update_metadata/get_metadata for offerings but provides no way to delete a stale offering's metadata, leaving abandoned entries permanently consuming instance storage. Add an owner-only remove_metadata(offering_id) that removes the Metadata(String) key and emits an event.

Requirements and Context

• Owner-gated remove_metadata(caller, offering_id) removing StorageKey::Metadata(offering_id).
• Emit metadata_removed with the offering id.
• get_metadata returns None afterward.
• Must be secure, tested, and documented
• Should be efficient and easy to review

Suggested Execution

1. Fork the repo and create a branch

   git checkout -b feature/vault-remove-metadata

2. Implement changes
   • contracts/vault/src/lib.rs — remove_metadata + event
   • EVENT_SCHEMA.md — document the event
3. Test and commit
   • cargo test -p callora-vault
   • Test remove then get_metadata returns None; owner-only enforced
   • Include test output and notes in the PR

Example commit message

feat: add remove_metadata to vault offering registry

Acceptance Criteria

• remove_metadata implemented and owner-gated
• metadata_removed event emitted
• get_metadata returns None after removal
• Tests cover removal and access control

Guidelines

• .rs under contracts/vault/src/, cargo test, /// docs, minimum 95% line coverage, no unwrap() in prod paths
• Clear documentation and inline comments
• Timeframe: 96 hours

[od-hunter]

Hello, can I be assigned this issue please? I've gone through the description and I'm up for the task. Kindly assign me please.

[dubemoyibe-star]

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

Hey can I work on this issue

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

[drips-wave]

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

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