* refactor(github): add GraphQL branch query adapter
Add infrastructure for querying GitHub branches via GraphQL:
- Add branches-query-adapter following the tags-query-adapter pattern
- Add GithubBranchItem type
- Export queryBranches function
- Register cache namespace
* style: fix prettier formatting
* test: add queryBranches coverage
* Refactor undefined checks to use `is.undefined`
Replace direct comparison of `undefined` with the `is.undefined` helper for consistency.
* refactor: use maxItems instead of maxPages
Sergei Zharinov