feat: add custom embedding types and migrate providers

- introduce baseembeddingsprovider and helper for embedding functions  
- add core embedding types and migrate providers, factory, and storage modules  
- remove unused type aliases and fix pydantic schema error  
- update providers with env var support and related fixes

src/crewai/memory/storage/rag_storage.py

@@ -7,8 +7,9 @@ from crewai.rag.chromadb.config import ChromaDBConfig
 from crewai.rag.chromadb.types import ChromaEmbeddingFunctionWrapper
 from crewai.rag.config.utils import get_rag_client
 from crewai.rag.core.base_client import BaseClient
-from crewai.rag.embeddings.factory import EmbedderConfig, get_embedding_function
-from crewai.rag.embeddings.types import EmbeddingOptions
+from crewai.rag.core.base_embeddings_provider import BaseEmbeddingsProvider
+from crewai.rag.embeddings.factory import build_embedder
+from crewai.rag.embeddings.types import ProviderSpec
 from crewai.rag.factory import create_client
 from crewai.rag.storage.base_rag_storage import BaseRAGStorage
 from crewai.rag.types import BaseRecord
@@ -26,7 +27,7 @@ class RAGStorage(BaseRAGStorage):
         self,
         type: str,
         allow_reset: bool = True,
-        embedder_config: EmbeddingOptions | EmbedderConfig | None = None,
+        embedder_config: ProviderSpec | BaseEmbeddingsProvider | None = None,
         crew: Any = None,
         path: str | None = None,
     ) -> None:
@@ -50,15 +51,17 @@ class RAGStorage(BaseRAGStorage):
         )
 
         if self.embedder_config:
-            embedding_function = get_embedding_function(self.embedder_config)
+            embedding_function = build_embedder(self.embedder_config)
 
             try:
                 _ = embedding_function(["test"])
             except Exception as e:
                 provider = (
-                    self.embedder_config.provider
-                    if isinstance(self.embedder_config, EmbeddingOptions)
-                    else self.embedder_config.get("provider", "unknown")
+                    self.embedder_config["provider"]
+                    if isinstance(self.embedder_config, dict)
+                    else self.embedder_config.__class__.__name__.replace(
+                        "Provider", ""
+                    ).lower()
                 )
                 raise ValueError(
                     f"Failed to initialize embedder. Please check your configuration or connection.\n"
@@ -80,7 +83,7 @@ class RAGStorage(BaseRAGStorage):
                     embedding_function=cast(
                         ChromaEmbeddingFunctionWrapper, embedding_function
                     ),
-                    batch_size=batch_size,
+                    batch_size=cast(int, batch_size),
                 )
             else:
                 config = ChromaDBConfig(
@@ -142,7 +145,7 @@ class RAGStorage(BaseRAGStorage):
                 client.add_documents(
                     collection_name=collection_name,
                     documents=[document],
-                    batch_size=batch_size,
+                    batch_size=cast(int, batch_size),
                 )
             else:
                 client.add_documents(