Add NFT events to `docs/events.md`

[Levi-Ojukwu]

Description:

The NFT module in contracts/invoice_liquidity/src/nft.rs emits three events that represent the lifecycle of invoice NFTs. These events are not documented in docs/events.md:

1. invoice_nft_minted — Emitted when an NFT is created for a new invoice. Contains invoice_id, owner, amount, due_date.

2. invoice_nft_transferred — Emitted when an NFT is transferred between addresses (e.g., freelancer to LP when invoice is funded). Contains invoice_id, from, to.

3. invoice_nft_burned — Emitted when an NFT is destroyed (e.g., when invoice is marked as paid). Contains invoice_id, owner.

These events are emitted using env.events().publish_event() at lines 101-107, 152-157, and 195-199 of nft.rs. Note: the current implementation uses the deprecated publish_event method — see Issue #26 for the migration.

Why it matters: NFT events enable indexers to track invoice ownership changes and build NFT marketplace features. Without documentation, developers cannot subscribe to or parse these events.

Acceptance Criteria:

• Document all three NFT events with their topic and data schemas
• Include example event payloads showing realistic data
• Note the deprecation status of publish_event and link to Issue Design and implement ReputationScore struct and storage #26

Relevant Files: docs/events.md, contracts/invoice_liquidity/src/nft.rs:100-200

---

[Dayz-tech-co]

Hi, I'd like to work on this issue. I've gone through the description and acceptance criteria and I'm confident I can deliver it. I'll make sure every acceptance criterion is met and submit a clean, tested PR. Please assign it to me.

[Henrichy]

@Henrichy has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi! I'd like to work on this issue.
I've contributed to Rust, TypeScript, backend, frontend, and smart contract projects, with a focus on delivering focused, well-tested changes. I'll keep the implementation within the requested scope, preserve existing behavior unless the issue requires otherwise, include the necessary tests and documentation, and submit a PR that's straightforward to review.
Portfolio: https://portfolio-sandy-alpha-29.vercel.app • ETA: ~2–4 hours.

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

[sunnykid-02]

@sunnykid-02 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

I’d like to work on this issue because complete event documentation is essential for developers building integrations with the protocol. Adding NFT events to docs/events.md will make it easier for indexers, wallets, and client applications to understand when events are emitted, what data they contain, and how to consume them correctly.

I have experience writing technical documentation, working with smart contracts, and documenting event-driven systems.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @sunnykid-02 to this issue.

[Henrichy]

@Levi-Ojukwu please assign to me. Would deliver in less than 2 hours

[akansmafengadamu]

@akansmafengadamu has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi there, can I work on this issue?

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