test: cover Builder Circle pool modes

[lntutor]

Summary

Adds coverage for parseBuilderCirclePoolMode across supported modes,
invalid and missing values, and mixed-case input.

Related issue

Fixes #39

Type of change

• Bug fix
• New feature
• Documentation
• Other: tests

How to test

1. Run npx tsx --test test/BuilderCircleMatching.ts.
2. Confirm all nine tests pass.

Checklist

• I ran npm run build (the current main branch has unrelated lint errors in meetup pages)
• I did not commit secrets or .env.local
• I read CONTRIBUTING.md

[lntutor]

Current head 6edf0ef is mergeable, and I do not see any unresolved review threads or contributor-side follow-up remaining on the current PR state. This looks ready for maintainer review when someone has a chance.

[FrankezeCode]

Thanks @Intutor for the clean test coverage for parseBuilderCirclePoolMode.
Merged! ✅
This closes the pool-mode parser testing for hybrid Builder Circles.