Adds 26 blackbox tests (FT-P-01..18, FT-N-01..08) covering full AC
matrices for Vehicles/Missions/Waypoints/Health/Errors. Three
spec-vs-code carry-forwards documented in batch_02_report.md and
pinned with [Trait("carry_forward", ...)].
Shared scaffolding: ApiDtos.cs, AssertProblemEnvelopeAsync helper,
Seeds.cs, StubSchema.cs, CascadeF3/F4 fixtures, PostgresStopStart
fixture (gated by COMPOSE_RESTART_ENABLED). Removes the 4 placeholder
Sanity.cs files (now superseded). docker-compose.test.yml gains the
expected_results volume mount + FIXTURE_SQL_DIR for the consumer.
Co-authored-by: Cursor <cursoragent@cursor.com>
Oleksandr Bezdieniezhnykh