feat: Add missing Vector Store Files API surface

This adds the ability to list, retrieve, update, and delete Vector
Store Files. It implements these new APIs for the faiss and sqlite-vec
providers, since those are the two that also have the rest of the
vector store files implementation.

There are a number of new integration tests added, which I ran for
each provider as outlined below.

faiss (from ollama distro):

```
INFERENCE_MODEL="meta-llama/Llama-3.2-3B-Instruct" \
llama stack run llama_stack/templates/ollama/run.yaml

LLAMA_STACK_CONFIG=http://localhost:8321 \
pytest -sv tests/integration/vector_io/test_openai_vector_stores.py \
  --embedding-model=all-MiniLM-L6-v2
```

sqlite-vec (from starter distro):

```
llama stack run llama_stack/templates/starter/run.yaml

LLAMA_STACK_CONFIG=http://localhost:8321 \
pytest -sv tests/integration/vector_io/test_openai_vector_stores.py \
  --embedding-model=all-MiniLM-L6-v2
```

Signed-off-by: Ben Browning <bbrownin@redhat.com>

llama_stack/providers/remote/vector_io/chroma/chroma.py

@@ -24,7 +24,11 @@ from llama_stack.apis.vector_io import (
     VectorStoreObject,
     VectorStoreSearchResponsePage,
 )
-from llama_stack.apis.vector_io.vector_io import VectorStoreChunkingStrategy, VectorStoreFileObject
+from llama_stack.apis.vector_io.vector_io import (
+    VectorStoreChunkingStrategy,
+    VectorStoreFileObject,
+    VectorStoreListFilesResponse,
+)
 from llama_stack.providers.datatypes import Api, VectorDBsProtocolPrivate
 from llama_stack.providers.inline.vector_io.chroma import ChromaVectorIOConfig as InlineChromaVectorIOConfig
 from llama_stack.providers.utils.memory.vector_store import (
@@ -263,3 +267,31 @@ class ChromaVectorIOAdapter(VectorIO, VectorDBsProtocolPrivate):
         chunking_strategy: VectorStoreChunkingStrategy | None = None,
     ) -> VectorStoreFileObject:
         raise NotImplementedError("OpenAI Vector Stores API is not supported in Chroma")
+
+    async def openai_list_files_in_vector_store(
+        self,
+        vector_store_id: str,
+    ) -> VectorStoreListFilesResponse:
+        raise NotImplementedError("OpenAI Vector Stores API is not supported in Chroma")
+
+    async def openai_retrieve_vector_store_file(
+        self,
+        vector_store_id: str,
+        file_id: str,
+    ) -> VectorStoreFileObject:
+        raise NotImplementedError("OpenAI Vector Stores API is not supported in Chroma")
+
+    async def openai_update_vector_store_file(
+        self,
+        vector_store_id: str,
+        file_id: str,
+        attributes: dict[str, Any] | None = None,
+    ) -> VectorStoreFileObject:
+        raise NotImplementedError("OpenAI Vector Stores API is not supported in Chroma")
+
+    async def openai_delete_vector_store_file(
+        self,
+        vector_store_id: str,
+        file_id: str,
+    ) -> VectorStoreFileObject:
+        raise NotImplementedError("OpenAI Vector Stores API is not supported in Chroma")

llama_stack/providers/remote/vector_io/milvus/milvus.py

@@ -26,7 +26,11 @@ from llama_stack.apis.vector_io import (
     VectorStoreObject,
     VectorStoreSearchResponsePage,
 )
-from llama_stack.apis.vector_io.vector_io import VectorStoreChunkingStrategy, VectorStoreFileObject
+from llama_stack.apis.vector_io.vector_io import (
+    VectorStoreChunkingStrategy,
+    VectorStoreFileObject,
+    VectorStoreListFilesResponse,
+)
 from llama_stack.providers.datatypes import Api, VectorDBsProtocolPrivate
 from llama_stack.providers.inline.vector_io.milvus import MilvusVectorIOConfig as InlineMilvusVectorIOConfig
 from llama_stack.providers.utils.memory.vector_store import (
@@ -262,6 +266,34 @@ class MilvusVectorIOAdapter(VectorIO, VectorDBsProtocolPrivate):
     ) -> VectorStoreFileObject:
         raise NotImplementedError("OpenAI Vector Stores API is not supported in Milvus")
 
+    async def openai_list_files_in_vector_store(
+        self,
+        vector_store_id: str,
+    ) -> VectorStoreListFilesResponse:
+        raise NotImplementedError("OpenAI Vector Stores API is not supported in Milvus")
+
+    async def openai_retrieve_vector_store_file(
+        self,
+        vector_store_id: str,
+        file_id: str,
+    ) -> VectorStoreFileObject:
+        raise NotImplementedError("OpenAI Vector Stores API is not supported in Milvus")
+
+    async def openai_update_vector_store_file(
+        self,
+        vector_store_id: str,
+        file_id: str,
+        attributes: dict[str, Any] | None = None,
+    ) -> VectorStoreFileObject:
+        raise NotImplementedError("OpenAI Vector Stores API is not supported in Milvus")
+
+    async def openai_delete_vector_store_file(
+        self,
+        vector_store_id: str,
+        file_id: str,
+    ) -> VectorStoreFileObject:
+        raise NotImplementedError("OpenAI Vector Stores API is not supported in Milvus")
+
 
 def generate_chunk_id(document_id: str, chunk_text: str) -> str:
     """Generate a unique chunk ID using a hash of document ID and chunk text."""

llama_stack/providers/remote/vector_io/qdrant/qdrant.py

@@ -24,7 +24,11 @@ from llama_stack.apis.vector_io import (
     VectorStoreObject,
     VectorStoreSearchResponsePage,
 )
-from llama_stack.apis.vector_io.vector_io import VectorStoreChunkingStrategy, VectorStoreFileObject
+from llama_stack.apis.vector_io.vector_io import (
+    VectorStoreChunkingStrategy,
+    VectorStoreFileObject,
+    VectorStoreListFilesResponse,
+)
 from llama_stack.providers.datatypes import Api, VectorDBsProtocolPrivate
 from llama_stack.providers.inline.vector_io.qdrant import QdrantVectorIOConfig as InlineQdrantVectorIOConfig
 from llama_stack.providers.utils.memory.vector_store import (
@@ -263,3 +267,31 @@ class QdrantVectorIOAdapter(VectorIO, VectorDBsProtocolPrivate):
         chunking_strategy: VectorStoreChunkingStrategy | None = None,
     ) -> VectorStoreFileObject:
         raise NotImplementedError("OpenAI Vector Stores API is not supported in Qdrant")
+
+    async def openai_list_files_in_vector_store(
+        self,
+        vector_store_id: str,
+    ) -> VectorStoreListFilesResponse:
+        raise NotImplementedError("OpenAI Vector Stores API is not supported in Qdrant")
+
+    async def openai_retrieve_vector_store_file(
+        self,
+        vector_store_id: str,
+        file_id: str,
+    ) -> VectorStoreFileObject:
+        raise NotImplementedError("OpenAI Vector Stores API is not supported in Qdrant")
+
+    async def openai_update_vector_store_file(
+        self,
+        vector_store_id: str,
+        file_id: str,
+        attributes: dict[str, Any] | None = None,
+    ) -> VectorStoreFileObject:
+        raise NotImplementedError("OpenAI Vector Stores API is not supported in Qdrant")
+
+    async def openai_delete_vector_store_file(
+        self,
+        vector_store_id: str,
+        file_id: str,
+    ) -> VectorStoreFileObject:
+        raise NotImplementedError("OpenAI Vector Stores API is not supported in Qdrant")