[AZ-232] Add safety anchor state machine

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

_docs/03_implementation/batch_09_cycle1_report.md

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+# Batch Report
+
+**Batch**: 9
+**Tasks**: AZ-232_safety_anchor_state_machine
+**Date**: 2026-05-03
+
+## Task Results
+
+| Task | Status | Files Modified | Tests | AC Coverage | Issues |
+|------|--------|----------------|-------|-------------|--------|
+| AZ-232_safety_anchor_state_machine | Done | 4 files | Pass | 4/4 ACs covered | None |
+
+## AC Test Coverage: All covered
+
+| AC Ref | Coverage |
+|--------|----------|
+| AZ-232 AC-1 | `test_vio_state_updates_position_estimate_with_honest_covariance` verifies VIO updates emit source-labelled estimates with honest covariance. |
+| AZ-232 AC-2 | `test_accepted_anchor_corrects_state_and_records_evidence` verifies accepted anchors promote `satellite_anchored` state and record evidence. |
+| AZ-232 AC-3 | `test_blackout_degrades_then_reaches_no_fix_with_monotonic_covariance` verifies monotonic covariance growth and no-fix semantics. |
+| AZ-232 AC-4 | `test_tile_write_eligibility_requires_trusted_low_covariance_pose` verifies conservative tile-write eligibility. |
+
+## Code Review Verdict: PASS
+
+Review report: `_docs/03_implementation/reviews/batch_09_review.md`
+
+## Auto-Fix Attempts: 0
+
+## Stuck Agents: None
+
+## Verification
+
+- `.venv/bin/python -m black --check src tests e2e/replay` passed.
+- `.venv/bin/python -m ruff check src tests e2e/replay` passed.
+- `.venv/bin/python -m pytest` passed: 49 tests.
+
+## Next Batch: All tasks complete