- Implement GetFileContentAtRef on *Client to satisfy vcs.PRReader interface
- Add escapePath and decodeBase64Content helpers
- Fix conformance_test.go to properly import and qualify github.Client
(was using unqualified Client in package github_test)
Fixes CI failure: the PRReader interface requires GetFileContentAtRef
but it was missing from this PR (only present in the file-reader PR).
claw