feat: allow returning embeddings and metadata from /vector_stores/ methods; disallow changing Provider ID (#4046)

# What does this PR do?

- Updates `/vector_stores/{vector_store_id}/files/{file_id}/content` to
allow returning `embeddings` and `metadata` using the `extra_query`
    -  Updates the UI accordingly to display them.

- Update UI to support CRUD operations in the Vector Stores section and
adds a new modal exposing the functionality.

- Updates Vector Store update to fail if a user tries to update Provider
ID (which doesn't make sense to allow)

```python
In  [1]: client.vector_stores.files.content(
    vector_store_id=vector_store.id, 
    file_id=file.id, 
    extra_query={"include_embeddings": True, "include_metadata": True}
)
Out [1]: FileContentResponse(attributes={}, content=[Content(text='This is a test document to check if embeddings are generated properly.\n', type='text', embedding=[0.33760684728622437, ...,], chunk_metadata={'chunk_id': '62a63ae0-c202-f060-1b86-0a688995b8d3', 'document_id': 'file-27291dbc679642ac94ffac6d2810c339', 'source': None, 'created_timestamp': 1762053437, 'updated_timestamp': 1762053437, 'chunk_window': '0-13', 'chunk_tokenizer': 'DEFAULT_TIKTOKEN_TOKENIZER', 'chunk_embedding_model': 'sentence-transformers/nomic
-ai/nomic-embed-text-v1.5', 'chunk_embedding_dimension': 768, 'content_token_count': 13, 'metadata_token_count': 9}, metadata={'filename': 'test-embedding.txt', 'chunk_id': '62a63ae0-c202-f060-1b86-0a688995b8d3', 'document_id': 'file-27291dbc679642ac94ffac6d2810c339', 'token_count': 13, 'metadata_token_count': 9})], file_id='file-27291dbc679642ac94ffac6d2810c339', filename='test-embedding.txt')
```

Screenshots of UI are displayed below:

### List Vector Store with Added "Create New Vector Store"
<img width="1912" height="491" alt="Screenshot 2025-11-06 at 10 47
25 PM"
src="https://github.com/user-attachments/assets/a3a3ddd9-758d-4005-ac9c-5047f03916f3"
/>

### Create New Vector Store
<img width="1918" height="1048" alt="Screenshot 2025-11-06 at 10 47
49 PM"
src="https://github.com/user-attachments/assets/b4dc0d31-696f-4e68-b109-27915090f158"
/>

### Edit Vector Store
<img width="1916" height="1355" alt="Screenshot 2025-11-06 at 10 48
32 PM"
src="https://github.com/user-attachments/assets/ec879c63-4cf7-489f-bb1e-57ccc7931414"
/>


### Vector Store Files Contents page (with Embeddings)
<img width="1914" height="849" alt="Screenshot 2025-11-06 at 11 54
32 PM"
src="https://github.com/user-attachments/assets/3095520d-0e90-41f7-83bd-652f6c3fbf27"
/>

### Vector Store Files Contents Details page (with Embeddings)
<img width="1916" height="1221" alt="Screenshot 2025-11-06 at 11 55
00 PM"
src="https://github.com/user-attachments/assets/e71dbdc5-5b49-472b-a43a-5785f58d196c"
/>

<!-- If resolving an issue, uncomment and update the line below -->
<!-- Closes #[issue-number] -->

## Test Plan
Tests added for Middleware extension and Provider failures.

---------

Signed-off-by: Francisco Javier Arceo <farceo@redhat.com>

src/llama_stack/apis/vector_io/vector_io.py

@@ -10,7 +10,7 @@
 # the root directory of this source tree.
 from typing import Annotated, Any, Literal, Protocol, runtime_checkable
 
-from fastapi import Body
+from fastapi import Body, Query
 from pydantic import BaseModel, Field
 
 from llama_stack.apis.common.tracing import telemetry_traceable
@@ -224,10 +224,16 @@ class VectorStoreContent(BaseModel):
 
     :param type: Content type, currently only "text" is supported
     :param text: The actual text content
+    :param embedding: Optional embedding vector for this content chunk
+    :param chunk_metadata: Optional chunk metadata
+    :param metadata: Optional user-defined metadata
     """
 
     type: Literal["text"]
     text: str
+    embedding: list[float] | None = None
+    chunk_metadata: ChunkMetadata | None = None
+    metadata: dict[str, Any] | None = None
 
 
 @json_schema_type
@@ -280,6 +286,22 @@ class VectorStoreDeleteResponse(BaseModel):
     deleted: bool = True
 
 
+@json_schema_type
+class VectorStoreFileContentResponse(BaseModel):
+    """Represents the parsed content of a vector store file.
+
+    :param object: The object type, which is always `vector_store.file_content.page`
+    :param data: Parsed content of the file
+    :param has_more: Indicates if there are more content pages to fetch
+    :param next_page: The token for the next page, if any
+    """
+
+    object: Literal["vector_store.file_content.page"] = "vector_store.file_content.page"
+    data: list[VectorStoreContent]
+    has_more: bool = False
+    next_page: str | None = None
+
+
 @json_schema_type
 class VectorStoreChunkingStrategyAuto(BaseModel):
     """Automatic chunking strategy for vector store files.
@@ -395,22 +417,6 @@ class VectorStoreListFilesResponse(BaseModel):
     has_more: bool = False
 
 
-@json_schema_type
-class VectorStoreFileContentResponse(BaseModel):
-    """Represents the parsed content of a vector store file.
-
-    :param object: The object type, which is always `vector_store.file_content.page`
-    :param data: Parsed content of the file
-    :param has_more: Indicates if there are more content pages to fetch
-    :param next_page: The token for the next page, if any
-    """
-
-    object: Literal["vector_store.file_content.page"] = "vector_store.file_content.page"
-    data: list[VectorStoreContent]
-    has_more: bool
-    next_page: str | None = None
-
-
 @json_schema_type
 class VectorStoreFileDeleteResponse(BaseModel):
     """Response from deleting a vector store file.
@@ -732,12 +738,16 @@ class VectorIO(Protocol):
         self,
         vector_store_id: str,
         file_id: str,
+        include_embeddings: Annotated[bool | None, Query(default=False)] = False,
+        include_metadata: Annotated[bool | None, Query(default=False)] = False,
     ) -> VectorStoreFileContentResponse:
         """Retrieves the contents of a vector store file.
 
         :param vector_store_id: The ID of the vector store containing the file to retrieve.
         :param file_id: The ID of the file to retrieve.
-        :returns: A VectorStoreFileContentResponse representing the file contents.
+        :param include_embeddings: Whether to include embedding vectors in the response.
+        :param include_metadata: Whether to include chunk metadata in the response.
+        :returns: File contents, optionally with embeddings and metadata based on query parameters.
         """
         ...