loadConfig() defaulted commit_docs to true regardless of whether
.planning/ was gitignored. The documented auto-detection only existed
inside cmdCommit, so init commands returned commit_docs: true even
when .planning/ was in .gitignore. This caused LLM executors to
bypass the cmdCommit gate and re-commit planning files with raw git.
Now loadConfig() checks isGitIgnored(cwd, '.planning/') when no
explicit commit_docs value is set in config.json. If .planning/ is
gitignored, commit_docs defaults to false. An explicit commit_docs
value in config.json is always respected.
Added 5 regression tests covering auto-detection, explicit overrides,
and the no-config-file edge case.
28166e4839