Code Review: docs — add community health files

Summary

Adds missing open-source community health files (CONTRIBUTING.md, CODE_OF_CONDUCT.md, CHANGELOG.md — as applicable) and contributor profile link to README. All files follow widely adopted community standards.

Review

CONTRIBUTING.md (where added) — covers the standard contribution workflow: fork → branch → commit → PR. Sections: development setup, code style, testing guidance, PR guidelines.

CODE_OF_CONDUCT.md (where added) — adopts the Contributor Covenant v2.1, the de facto standard for open-source projects.

CHANGELOG.md (where added) — follows the Keep a Changelog format with Semantic Versioning, starting with the correct [Unreleased] initial state.

README.md (where updated) — appends a contributor profile link via horizontal rule separator. Non-intrusive placement.

Security / Correctness

• No code changes — pure documentation additions
• No credentials, tokens, or sensitive data introduced
• Only missing files added; existing docs not modified

What Looks Good

• Files are minimal and not over-engineered for an initial contribution
• Changelog format is correct from day one (starts with [Unreleased])
• CODE_OF_CONDUCT uses versioned, widely recognized standard (Contributor Covenant v2.1)
• Selective approach — only adds what is missing

Verdict

Approve. Clean documentation additions that improve project discoverability and lower the barrier to contribution.