refactor(01-07): factor_graph, pipeline pkg, testing/benchmark, Protocol ABCs

- Create core/factor_graph.py: IFactorGraphOptimizer converted to Protocol
- Shim core/graph.py to re-export from core/factor_graph
- Create pipeline/ package: orchestrator, image_input, result_manager, sse_streamer
- Shim core/{processor,pipeline,results,sse}.py to re-export from pipeline/
- Create testing/benchmark.py; shim core/benchmark.py
- Convert IRouteChunkManager, IFailureRecoveryCoordinator, IModelManager, IImageMatcher to Protocol
- Update pyproject.toml ruff per-file-ignores to new paths
- All 216 tests pass (regression floor maintained)

src/gps_denied/pipeline/__init__.py

@@ -0,0 +1,15 @@
+"""Pipeline package: orchestrator + IO + composition root."""
+from .orchestrator import FlightProcessor
+from .image_input import ImageInputPipeline
+from .result_manager import ResultManager
+from .sse_streamer import SSEEventStreamer
+
+Pipeline = FlightProcessor
+
+__all__ = [
+    "FlightProcessor",
+    "Pipeline",
+    "ImageInputPipeline",
+    "ResultManager",
+    "SSEEventStreamer",
+]