Update README

Refresh an existing README.md using current codebase state, git history, and changelog intelligence. Always updates CHANGELOG.md first so changelog content is available when revising README sections.

Step 1 — Check README Existence

Glob for README.md, readme.md, and Readme.md in the working directory.

If not found, or if the file has fewer than 5 lines of real content:

• Inform the user no substantial README was found
• Invoke Skill: claude-coding:make-readme
• Stop — make-readme handles creation from scratch

If a substantial README exists: continue.

Step 2 — Update Changelog