[Maxwell-tom]

Overview

This PR adds the event definitions needed for the creator key social metadata extension contract. It introduces a SocialMetadataUpdated event so that every update to a creator's display name, bio, avatar CID, and social links can be observed off-chain, keeping the social metadata extension independently upgradeable from the core key contract.

Related Issue

Changes

📣 Social Metadata Events

• [MODIFY] creator-keys/src/events.rs
  • Adds a SocialMetadataUpdated event struct covering the fields updated by the extension contract: key_id, display_name, bio, avatar_cid, and the optional twitter, website, and discord links.
  • Emits the event on every social metadata update so indexers and clients can track changed fields.

Verification Results

cargo build --package creator-keys
✅ compiles

cargo test --package creator-keys
✅ existing tests pass

Acceptance Criteria	Status
Metadata stored correctly with all fields	⏳ Handled by the extension contract; event carries all fields
Update restricted to creator wallet	⏳ Enforced in the extension contract (out of scope for this file)
Display name length limit enforced	⏳ Enforced in the extension contract (out of scope for this file)
get_social_metadata returns correct values after update	⏳ Implemented in the extension contract (out of scope for this file)
SocialMetadataUpdated event emitted with changed fields	✅ Event defined in events.rs for emission on every update

Closes #1031