buildNewProjectConfig() merges ~/.gsd/defaults.json when present, so
tests asserting concrete config values (model_profile, commit_docs,
brave_search) would fail on machines with a personal defaults file.
- Pass HOME=cwd as env override in runGsdTools — child process resolves
os.homedir() to the temp directory, which has no .gsd/ subtree
- Update three tests that previously wrote to the real ~/.gsd/ using
fragile save/restore logic; they now write to tmpDir/.gsd/ instead,
which is cleaned up automatically by afterEach
- Remove now-unused `os` import from config.test.cjs
63f6424d1b