[AZ-423] [AZ-427] Add FT-P-19 + FT-N-05 blackbox tests

Implement the AC-8.6 (top-K=10 retrieval scale-ratio + scene-change
PARTIAL) and AC-8.2 / AC-NEW-6 (stale aged-tile rejection) blackbox
scenarios.

AZ-423 (FT-P-19, 3pt) helpers + scenario:
- retrieval_evaluator.py — top-K within-distance evaluator (60 stills
  vs 100 m budget), scene-change PARTIAL recorder (always emits
  PARTIAL on the 2 _gmaps.png pairs), FDR record projectors, CSV
  writers.
- tests/positive/test_ft_p_19_sat_reloc_scale.py (6 parametrised
  variants).

AZ-427 (FT-N-05, 2pt) helpers + scenario:
- aged_tile_rejection_evaluator.py — Signal A (stale rejection at
  load) + Signal B (per-frame downgrade) decision matrix, reuses
  ALLOWED_SOURCE_LABELS from estimate_schema.
- tests/negative/test_ft_n_05_stale_tile_rejection.py (12 parametrised
  variants: FC × VIO × {7mo/active-conflict, 13mo/rear}).

48 new unit tests cover every helper branch. Both scenarios skip
when sitl_replay_ready is false and fail loudly when fixture records
are missing.

Per-batch review: PASS_WITH_WARNINGS (2 Low — production-dependency
surface, FDR-kind constant duplication).
Cumulative review 82-84: PASS (2 Low carry-over / hygiene candidate).

Co-authored-by: Cursor <cursoragent@cursor.com>

_docs/_autodev_state.md

@@ -12,9 +12,9 @@ sub_step:
 retry_count: 0
 cycle: 1
 tracker: jira
-last_completed_batch: 83
-last_cumulative_review: batches_79-81
-current_batch: 84
+last_completed_batch: 84
+last_cumulative_review: batches_82-84
+current_batch: 85
 
 last_step_outcomes:
   step_8: "Code is testable — no changes needed (testability_assessment.md committed; no list-of-changes, no source edits)"