feat(01-02): add Phase-3/4 stub Protocols (anchor_verifier, safety_state, flight_recorder)

- anchor_verifier.protocol: AnchorVerifier + VerifierDecision dataclass
  (Phase 3 VERIFY-01..05 fills semantics)
- safety_state.protocol: SafetyAnchorStateMachine + SourceLabel enum
  (Phase 3 SAFE-01..06 fills implementation)
- flight_recorder.protocol: FlightRecorder + RecorderHealth enum +
  FdrExportResult (Phase 4 FDR-01..06 fills)
- Enum string values match REQUIREMENTS.md SAFE-01 / FDR-04
- Not registered in build_pipeline yet — Phase 1 only requires existence

src/gps_denied/components/anchor_verifier/protocol.py

@@ -0,0 +1,37 @@
+"""Protocol surface for the anchor_verifier component (Phase 3, VERIFY-01..05).
+
+Phase 1: stub only — semantics filled in Phase 3. The Protocol must
+exist now so the ARCH-01 directory inventory is complete at end of
+Phase 1.
+"""
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Protocol, runtime_checkable
+
+from gps_denied.hot_types.alignment_result import AlignmentResult
+from gps_denied.hot_types.satellite_anchor import SatelliteAnchor
+
+
+@dataclass(slots=True, frozen=True)
+class VerifierDecision:
+    """Result of an :meth:`AnchorVerifier.verify` call.
+
+    Phase 3 will refine the rejection-reason taxonomy (currently free-text:
+    ``too_few_inliers`` / ``mre_above_threshold`` / ``degenerate_homography``
+    / ``freshness_expired``).
+    """
+
+    accepted: bool
+    anchor: SatelliteAnchor | None = None
+    rejection_reason: str | None = None
+    inlier_count: int = 0
+    mean_reprojection_error_px: float = 0.0
+    homography_condition_number: float = 0.0
+
+
+@runtime_checkable
+class AnchorVerifier(Protocol):
+    """Geometry-gated anchor verifier. Filled in Phase 3."""
+
+    def verify(self, candidate: AlignmentResult) -> VerifierDecision: ...