Add file.flush() call in append_entry() to ensure planner history
entries are written to disk before git commits execute. While the
file handle drop should flush, explicit flush simplifies reasoning
about the ordering invariant.
Extend code comments in stage_and_commit() to document that the
write_git_commit-before-git::commit ordering has regressed multiple
times and must be preserved in any refactoring.
Requirements: completed_requirements_2025-12-11_10-05-08.md
Ensure planner writes GIT COMMIT entry before invoking git commit.
Keep history entry even when git commit fails, matching summary text.
Document invariant in code comment above write_git_commit call.
Add lightweight test to assert history write precedes git::commit using
test doubles instead of a real git repository.
Investigate git history to find regression and its prior fix, and
record a short root-cause summary outside the codebase.
Reference completed_requirements_2025-12-10_16-55-05.md for details.
Reference completed_todo_2025-12-10_16-55-05.md for task tracking.
