Add fast slab lookup for the GeometryOracle, replacing knn as the default

miniCaloSim's detector is a stack of planar layer slabs along one axis, so
material/layer_id are a pure function of depth. The new "slab" method
exploits this with an exact O(log #segments) binary search over
depth-axis segment boundaries, instead of a nearest-neighbour search over
hundreds of thousands of reference points — much cheaper per call, which
matters since the oracle is queried on every autoregressive rollout step.
"knn"/"svm" remain as fallbacks for non-slab geometries.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

scripts/dwarf.py

@@ -387,6 +387,7 @@ def make_root(
 
 
 class OracleMethod(str, Enum):
+    slab = "slab"
     knn = "knn"
     svm = "svm"
 
@@ -396,13 +397,18 @@ def build_geometry_oracle(
     data: Annotated[
         Path, typer.Argument(help="Steps parquet file or directory of steps files")
     ],
-    out: Annotated[
-        Path, typer.Option("--out", "-o", help="Output oracle .pkl path")
-    ],
+    out: Annotated[Path, typer.Option("--out", "-o", help="Output oracle .pkl path")],
     method: Annotated[
         OracleMethod,
-        typer.Option("--method", help="Classifier: knn (default) or svm"),
-    ] = OracleMethod.knn,
+        typer.Option(
+            "--method",
+            help=(
+                "Lookup strategy: slab (default; exact O(log #segments) fast "
+                "path for the layered-slab detector geometry), knn, or svm "
+                "(generic fallbacks for non-slab geometries)"
+            ),
+        ),
+    ] = OracleMethod.slab,
     k: Annotated[
         int, typer.Option("--k", help="Neighbours for the knn classifier")
     ] = 1,
@@ -414,10 +420,24 @@ def build_geometry_oracle(
         float,
         typer.Option(
             "--escape-factor",
-            help="escape_threshold = this x median NN spacing of reference points",
+            help="escape_threshold = this x median spacing of reference points",
         ),
     ] = 5.0,
     seed: Annotated[int, typer.Option("--seed", help="Sampling seed")] = 0,
+    depth_axis: Annotated[
+        int,
+        typer.Option(
+            "--depth-axis",
+            help="0/1/2 -> x/y/z axis the layers stack along (method=slab only)",
+        ),
+    ] = 2,
+    n_bins: Annotated[
+        int,
+        typer.Option(
+            "--n-bins",
+            help="Depth-axis resolution, finer than the thinnest layer (method=slab only)",
+        ),
+    ] = 2000,
 ) -> None:
     """Fit a position -> (material, layer_id) oracle for `giant rollout`."""
     run_build_geometry_oracle(
@@ -428,6 +448,8 @@ def build_geometry_oracle(
         subsample=subsample,
         escape_factor=escape_factor,
         seed=seed,
+        depth_axis=depth_axis,
+        n_bins=n_bins,
     )