Unit tests for parseGithubRef #88

What

parseGithubRef in lib/pr-journey.ts turns a GitHub PR/issue URL into { owner, repo, number, kind }. Every milestone submission goes through it.

There are no tests for it yet.

Cover at least

• a PR URL → kind: "pr", and an issue URL → kind: "issue"
• www.github.com, http://, and trailing /files or #discussion still parse
• surrounding whitespace is ignored
• non-GitHub URLs, a repo URL with no number, and gitlab.com URLs return null
• owner/repo names with dots and hyphens

How

• Create lib/pr-journey.test.ts next to the code. Follow the style of lib/github-auth.test.ts.
• Run npm test. Then break the code on purpose (flip a condition) and watch at least one of your tests fail. Paste that failure output in the PR description, then undo the break.
• Test behaviour through the exported function only. Don't change the source file unless you find a bug, and if you do, stop and comment on this issue first.

Size: ~30–60 lines of tests, 0 lines of source.

Taking this? Comment /assign and the bot assigns you if it's free. One issue per person at a time; comment /unassign to hand it back. That's milestone 2 of the 10 PR Journey. Setup, the checks CI runs, and how to open the PR from your fork are in CONTRIBUTING.md. Put Fixes #<this issue> in your PR description.