feat(01-08): add pipeline/composition.py with env-aware build_pipeline factory

- Create build_pipeline(env, config, repository, streamer) -> FlightProcessor
- Wires all components: VO, GPR, MetricRefinement, FactorGraph, ChunkManager,
  FailureRecovery, ImageRotationManager, CoordinateTransformer, SatelliteDataManager, MAVLinkBridge
- env=jetson: prefer_cuvslam=True, prefer_mono_depth=True
- env=x86_dev/ci/sitl: prefer_cuvslam=False, prefer_mono_depth=False
- ci env: MAVLink instantiation failures are tolerated (None fallback)
- Export build_pipeline from pipeline/__init__.py

src/gps_denied/pipeline/__init__.py

@@ -3,6 +3,7 @@ from .orchestrator import FlightProcessor
 from .image_input import ImageInputPipeline
 from .result_manager import ResultManager
 from .sse_streamer import SSEEventStreamer
+from .composition import build_pipeline
 
 Pipeline = FlightProcessor
 
@@ -12,4 +13,5 @@ __all__ = [
     "ImageInputPipeline",
     "ResultManager",
     "SSEEventStreamer",
+    "build_pipeline",
 ]