perf: unify spatial interaction queries

Dense drawings previously rescanned full geometry for snapping, tracking, and selection.\n\nRefs #433

src/scene/pick/mod.rs

@@ -1,6 +1,6 @@
-pub mod hit_test;
-pub mod selection_state;
 pub mod grip;
+pub mod hit_test;
+pub mod interaction_index;
 pub mod quadtree;
-pub mod wire_grid;
+pub mod selection_state;
 pub mod xclip;