Purpose
-------
Tests for the changelog generator (Phase 4E — G-E1, G-E2, G-E10).
Responsibilities
----------------
- Validate ``collect_changelog_entries`` parsing and filtering.
- Validate ``format_changelog`` output format (Keep a Changelog).
- Validate ``changelog_to_json`` structured output.
- Integration tests for ``oct git changelog`` CLI command.
Diagnostics
-----------
Domain: GIT-TESTS
Levels:
L2 — test lifecycle
L3 — test details
L4 — deep tracing
Contracts
---------
- All tests use the ``temp_git_project`` fixture from conftest.
- CLI tests use subprocess invocation.