Add PocketPay SDK PR reviewer evidence checklist

[El-swaggerito]

Description

Difficulty: Hard

Type: Documentation

Summary

Create a reviewer evidence checklist for PocketPay SDK maintainers.

Current Behaviour

Reviewers may merge contributor PRs without consistently checking tests, CI, acceptance criteria, and documentation impact.

Expected Behaviour

Maintainers should have a checklist for reviewing whether a PR is complete and evaluation-ready.

Suggested Implementation

Add reviewer guidance covering scope, implementation quality, tests, CI, docs, acceptance criteria, and risk.

Files or Areas Likely Affected

• src/
• tests/
• docs/
• README.md
• .github/
• package.json

Acceptance Criteria

• Reviewer evidence checklist is added.
• Implementation scope is checked.
• Test evidence is checked.
• CI status is checked.
• Acceptance criteria are checked.
• README links to reviewer guidance.

Additional Notes

This improves maintainer-side quality control.