Add tests/unit/test_config.py with pytestmark=pytest.mark.unit so the
tests are picked up by tox -e unit. Covers:
- normalize_ollama_url helper (6 cases)
- Settings defaults for all major fields
- normalized_ollama_url property
- Env var overrides for strings, bools, ints, floats, Literals
- Type validation and pydantic ValidationError paths
- Edge cases: empty strings, zero/negative ints, large values
- _compute_repo_root auto-detection
- model_post_init gitea_token file fallback
- check_ollama_model_available (OSError, found, not found, exact match, startswith)
- get_effective_ollama_model fallback chain
- validate_startup: test-mode skip, dev warnings, production sys.exit guards
- APP_START_TIME and module-level settings singleton
Refs #1172
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
