refactor: Transformer更名为AutoRegressiveLM并新增EmbeddingEncoder

- AutoRegressiveLM 注册名改为 autoregressive_lm
- 新增 EmbeddingEncoder 支持 mean/cls/last pooling
- ModelConfig 增加 pooling_type / normalize_embeddings 字段
- 导入、注释、测试全部同步更新

astrai/__init__.py

@@ -2,7 +2,8 @@ __version__ = "1.3.5"
 __author__ = "ViperEkura"
 
 from astrai.config import (
-    ModelConfig,
+    AutoRegressiveLMConfig,
+    EncoderConfig,
     TrainConfig,
 )
 from astrai.dataset import DatasetFactory
@@ -11,13 +12,14 @@ from astrai.inference import (
     GenerationRequest,
     InferenceEngine,
 )
-from astrai.model import AutoModel, Transformer
+from astrai.model import AutoModel, AutoRegressiveLM
 from astrai.tokenize import AutoTokenizer
 from astrai.trainer import CallbackFactory, SchedulerFactory, StrategyFactory, Trainer
 
 __all__ = [
-    "Transformer",
-    "ModelConfig",
+    "AutoRegressiveLM",
+    "AutoRegressiveLMConfig",
+    "EncoderConfig",
     "TrainConfig",
     "DatasetFactory",
     "AutoTokenizer",