All 5 ACs verified clean: field mapping, safe defaults, timeout propagation,
MLAT detection, and FileFixtureFetcher. 64 tests pass, ruff check and format
clean. Sprint status updated to done, deferred-work updated with runtime
verification note for HttpFetcher on live dump1090.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Add HttpFetcher and FileFixtureFetcher with shared _parse_aircraft helper,
DUMP1090_URL constant, realistic fixture data, and full test coverage for
all acceptance criteria (AC1–AC5).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Matt Edholm