[AZ-918] [AZ-919] [AZ-920] [AZ-921] [AZ-922] VIO/ESKF baseline fixes

Derkachi e2e Tier-2 divergence had three stacked root causes; this
commit ships fixes for all three plus the IMU prerequisite they
depend on, plus a baseline cheirality gate for cv2.recoverPose.

AZ-918  MAVLink IMU adapters now convert raw mG/mrad-s + FRD body to
        SI m/s^2 + rad/s + FLU body via helpers.imu_units. Without
        this the ESKF receives values ~1000x too small with wrong-
        sign Y/Z and cannot function at all.

AZ-919  Composition root wires EskfNominalAltitudeProvider into the
        KLT/RANSAC strategy via the AZ-331 factory introspect path;
        OKVIS2 and VINS-Mono are unaffected.

AZ-920  KLT/RANSAC recovers metric translation via Ground Sampling
        Distance when AGL is available; otherwise falls through with
        scale_quality=direction_only/unknown (no fake scale invented).

AZ-921  VioOutput.scale_quality signal; ESKF add_vio adapts R_meas
        position block based on the flag (1e6 inflation when scale is
        direction_only/unknown to keep the filter consistent).

AZ-922  KLT/RANSAC cheirality gate rejects single-frame rotations
        beyond a config threshold (default 30 deg), catching
        cv2.recoverPose twisted-pair flips that cause immediate ESKF
        divergence on low-parallax aerial scenes.

Verification:
- Tier-1 (macOS) unit suite: 2346 passed, 0 failed.
- Tier-2 (Jetson) Derkachi e2e: divergence moves from frame 5
  (mahalanobis^2 3757) to frame 233 (mahalanobis^2 212). Remaining
  drift is open-loop attitude accumulation, not cheirality.

Follow-up tickets filed:
- AZ-923 closed as misdiagnosed: EskfNominalAltitudeProvider was
  already correct (nominal_pos.z IS the AGL when takeoff origin sits
  at ground level); the early-frame AGL near zero reflects the drone
  being stationary on the ground, not a provider bug.
- AZ-942 filed: cross-check VIO rotation against IMU preintegrator
  (consistency gate) - more physically grounded than the coarse
  AZ-922 threshold and likely required to absorb the frame-233 drift.

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

tests/unit/c1_vio/test_klt_ransac_strategy.py

@@ -53,7 +53,6 @@ from gps_denied_onboard.config.schema import Config, RuntimeConfig
 from gps_denied_onboard.fdr_client.client import FdrClient
 from gps_denied_onboard.fdr_client.records import FdrRecord
 
-
 # ----------------------------------------------------------------------
 # Helpers — keep boilerplate out of the AC test bodies.
 
@@ -528,6 +527,19 @@ def test_ac6_low_inlier_count_emits_degraded_with_monotonic_covariance(
         calibration,
     )
 
+    # AZ-922 — pin cv2.recoverPose to identity rotation for frame 2 too.
+    # Real cv2 on this synthetic input returns a near-180° rotation that
+    # the cheirality gate would reject; this test asserts FACADE state
+    # classification on inlier loss, not cv2's geometry on synthetic data.
+    def _identity_recover_pose(
+        *_a: Any, **_k: Any
+    ) -> tuple[int, np.ndarray, np.ndarray, np.ndarray]:
+        R = np.eye(3, dtype=np.float64)
+        t = np.array([[0.01], [0.0], [0.0]], dtype=np.float64)
+        return 1, R, t, np.ones((1, 1), dtype=np.uint8)
+
+    monkeypatch.setattr(klt_ransac_module.cv2, "recoverPose", _identity_recover_pose)
+
     # Frame 2 — first successful pose recovery (TRACKING).
     out_tracking = strategy.process_frame(
         _frame(idx=2, image=_synthetic_frame_image(seed=31, shift_x=3)),