fix: Import load_model_from_npz from serialization (no Hydra dependency)

Fixes runtime error: ModuleNotFoundError: No module named 'hydra'

Changed internal imports to avoid pulling in Hydra for inference-only code.
load_model_from_npz lives in serialization.py which has no Hydra dependency.

src/antibody_training_esm/core/__init__.py

@@ -10,7 +10,7 @@ Professional ML components for antibody classification:
 
 from antibody_training_esm.core.classifier import BinaryClassifier
 from antibody_training_esm.core.embeddings import ESMEmbeddingExtractor
-from antibody_training_esm.core.trainer import load_model_from_npz
+from antibody_training_esm.core.training.serialization import load_model_from_npz
 
 __all__ = [
     "BinaryClassifier",

src/antibody_training_esm/core/prediction.py

@@ -12,7 +12,7 @@ from sklearn.linear_model import LogisticRegression
 from antibody_training_esm.core.classifier import BinaryClassifier
 from antibody_training_esm.core.config import DEFAULT_BATCH_SIZE
 from antibody_training_esm.core.embeddings import ESMEmbeddingExtractor
-from antibody_training_esm.core.trainer import load_model_from_npz
+from antibody_training_esm.core.training.serialization import load_model_from_npz
 from antibody_training_esm.models.prediction import (
     AssayType,
     PredictionRequest,