[Docs] Fix get_escrow comment vs return type mismatch

[Jayrodri088]

Complexity / points: Trivial (100 points) - maintainer label: points-100-trivial

PR must include:

• Closes #21 in the PR description
• Tests added or updated where behavior changes
• Docs updated if public API, lifecycle, or deploy steps change
• No unwrap() in production Soroban contract paths (project convention)
• cargo test passes locally; match CI (cargo fmt, cargo clippy -D warnings) when touching Rust

Problem

In contracts/invoice-escrow/src/lib.rs, the comment for get_escrow says it returns Γò¼├┤Γö£ΓòóΓö¼├║╬ô├╢┬ú╬ô├╢├⌐╬ô├▓┬╝Γö£Γöñ╬ô├╢┬ú╬ô├«├ë╬ô├╢┬╝╬ô├▓┬ÑΓò¼├┤Γö£Γòó╬ô├▓┬Ñ╬ô├╢┬ú╬ô├╢├▒escrow data for an invoice, or None if not found.Γò¼├┤Γö£ΓòóΓö¼├║╬ô├╢┬ú╬ô├╢├⌐╬ô├▓┬╝Γö£Γöñ╬ô├╢┬ú╬ô├«├ë╬ô├╢┬╝╬ô├▓┬Ñ^]

But the function signature is:

• pub fn get_escrow(...) -> Result<EscrowData, Error>
• and it returns Err(Error::EscrowNotFound) when missing

So the code behavior does not match the documented intent.

Proposed change

Fix the mismatch so documentation and behavior agree.

Acceptance criteria

• Update the get_escrow rustdoc comment to accurately reflect Result + Error::EscrowNotFound
• Ensure any related docs (e.g., docs/API.md once created) describe the same behavior
• Optional: add/adjust a unit test asserting missing invoice_id returns Error::EscrowNotFound

Dependencies

Recommended after or together with [Docs] Add missing docs/API.md... so the new API doc and rustdoc stay consistent.

[Jayrodri088]

Deferred (Wave 1 scope)
Maintainers are focusing this wave on implementation: escrow, invoice-token lifecycle, settlement/payment flows, payment-distributor, tests, and security bugs — aligned with decentralized invoice factoring on Stellar (liquidity for sellers, yield for investors, on-chain escrow/settlement).

Documentation issues will be reopened or recreated in a later wave. If you already started work, comment here and we can link a follow-up issue.