feat(01-03): move create_vo_backend factory into components/vio/factory.py

- Lift the env-aware VO backend factory verbatim from core/vo.py.
- Body and parameter defaults preserved exactly (PATTERNS.md §4.1
  mandate: 'Preserve this factory verbatim').
- Return-type annotation widened from ISequentialVisualOdometry to the
  canonical VisualOdometry Protocol from Plan 01-02; the I-prefix alias
  is still importable so legacy callers/type-checkers keep working.
- Imports route through the new components.vio.* modules; no
  cross-package edits needed because Plan 08 (composition root) is the
  only other call site planned.
- Append to the components.vio barrel.

src/gps_denied/components/vio/__init__.py

@@ -24,6 +24,7 @@ from gps_denied.components.vio.cuvslam_backend import (
     CuVSLAMMonoDepthVisualOdometry,
     CuVSLAMVisualOdometry,
 )
+from gps_denied.components.vio.factory import create_vo_backend
 
 __all__ = [
     "VisualOdometry",
@@ -32,4 +33,5 @@ __all__ = [
     "SequentialVisualOdometry",
     "CuVSLAMVisualOdometry",
     "CuVSLAMMonoDepthVisualOdometry",
+    "create_vo_backend",
 ]

src/gps_denied/components/vio/factory.py

@@ -0,0 +1,67 @@
+"""VIO backend factory — env-aware DI seed (ARCH-01 / ARCH-03).
+
+Preserves ``create_vo_backend`` verbatim from the legacy ``core/vo.py``
+location. PATTERNS.md §4.1 explicitly designates this factory as the
+seed of the env-aware composition root: ``pipeline/composition.py``
+(Plan 08) will pass env-specific kwargs (``prefer_cuvslam``,
+``prefer_mono_depth``, ``model_manager``) into this function from
+``RuntimeConfig``.
+
+Signature contract for Plan 08 wiring:
+
+  - ``env="jetson"``           → prefer_cuvslam=True,  prefer_mono_depth=True
+  - ``env="x86_dev" | "ci"``   → prefer_cuvslam=False, model_manager=mock
+  - ``env="sitl"``             → prefer_cuvslam=False
+"""
+from __future__ import annotations
+
+from typing import Optional
+
+from gps_denied.components.vio.cuvslam_backend import (
+    CuVSLAMMonoDepthVisualOdometry,
+    CuVSLAMVisualOdometry,
+)
+from gps_denied.components.vio.orbslam_backend import (
+    ORBVisualOdometry,
+    SequentialVisualOdometry,
+)
+from gps_denied.components.vio.protocol import VisualOdometry
+from gps_denied.core.models import IModelManager
+from gps_denied.schemas import CameraParameters
+
+
+def create_vo_backend(
+    model_manager: Optional[IModelManager] = None,
+    prefer_cuvslam: bool = True,
+    prefer_mono_depth: bool = False,
+    camera_params: Optional[CameraParameters] = None,
+    imu_params: Optional[dict] = None,
+    depth_hint_m: float = 600.0,
+) -> VisualOdometry:
+    """Return the best available VO backend for the current platform.
+
+    Priority when prefer_mono_depth=True:
+      1. CuVSLAMMonoDepthVisualOdometry (sprint 1 production path)
+      2. ORBVisualOdometry (dev/CI fallback inside Mono-Depth wrapper)
+
+    Priority when prefer_mono_depth=False (legacy):
+      1. CuVSLAMVisualOdometry (Jetson — cuVSLAM SDK present)
+      2. SequentialVisualOdometry (TRT/Mock SuperPoint+LightGlue)
+      3. ORBVisualOdometry (pure OpenCV fallback)
+    """
+    if prefer_mono_depth:
+        return CuVSLAMMonoDepthVisualOdometry(
+            depth_hint_m=depth_hint_m,
+            camera_params=camera_params,
+            imu_params=imu_params,
+        )
+
+    if prefer_cuvslam:
+        vo = CuVSLAMVisualOdometry(camera_params=camera_params, imu_params=imu_params)
+        if vo._has_cuvslam:
+            return vo
+
+    if model_manager is not None:
+        return SequentialVisualOdometry(model_manager)
+
+    return ORBVisualOdometry()