feat(scenegraph): add ImageHashPipeline protocol and update query API

- Introduce ImageHashPipeline Protocol for extensible hash computation
- Rename query_crop_index to query_index for clarity
- Make query_crop nullable to handle missing crop edge case
- Add keyword-only arguments for better API clarity
- Handle empty scene graph objects gracefully
- Add comprehensive test coverage for query_image_against_scene_graph

mini-nav/scenegraph/__init__.py

@@ -2,7 +2,7 @@
 
 This module exports the main scenegraph objects for easy import:
 
-from mini_nav.scenegraph import SimpleSceneGraph, RoomNode, ObjectNode
+from scenegraph import SimpleSceneGraph, RoomNode, ObjectNode
 """
 
 from .hash_codec import (
@@ -13,13 +13,18 @@ from .hash_codec import (
     hash_bytes_to_cam_row,
 )
 from .objectnode import ObjectNode
-from .query import ImageSceneGraphQueryResult, query_image_against_scene_graph
+from .query import (
+    ImageHashPipeline,
+    ImageSceneGraphQueryResult,
+    query_image_against_scene_graph,
+)
 from .roomnode import RoomNode
 from .scenegraph import SceneGraphMatch, SimpleSceneGraph
 from .software_cam import CamMatch, SoftwareCamIndex, xnor_popcount_score
 
 __all__ = [
     "CamMatch",
+    "ImageHashPipeline",
     "ImageSceneGraphQueryResult",
     "ObjectNode",
     "RoomNode",