amygdala: drop linear_aggregator, not in steering-vectors v0.12.2

Only mean/pca/logistic are exposed in the installed version.
Co-Authored-By: Proof of Concept <poc@bcachefs.org>

training/amygdala_training/train_with_library.py

@@ -41,7 +41,6 @@ from steering_vectors.aggregators import (
     mean_aggregator,
     pca_aggregator,
     logistic_aggregator,
-    linear_aggregator,
 )
 
 # Reuse corpus loader from the hand-rolled trainer.
@@ -96,8 +95,6 @@ def _aggregator_from_name(name: str):
         return logistic_aggregator(
             sklearn_kwargs={"penalty": "l1", "solver": "liblinear", "C": 0.1}
         )
-    if name == "linear":
-        return linear_aggregator()
     raise ValueError(f"unknown aggregator: {name}")
 
 
@@ -116,7 +113,7 @@ def main() -> None:
     ap.add_argument(
         "--aggregator",
         default="mean",
-        choices=["mean", "pca", "logistic", "logistic_l1", "linear"],
+        choices=["mean", "pca", "logistic", "logistic_l1"],
     )
     ap.add_argument("--max-negatives-per-positive", type=int, default=3)
     args = ap.parse_args()