fix(s3_vectors): list() wraps results in an extra list, breaking callers

[devteamaegis]

What's broken

S3VectorStore.list() returns List[List[OutputData]] instead of List[OutputData]:

store = S3VectorStore(...)
results = store.list()
# results is [[OutputData(...), OutputData(...)]]  ← nested list
# should be   [OutputData(...), OutputData(...)]

Any caller that iterates over the result gets a single inner list as the first element, not the actual records.

Why it happens

The return statement wraps _parse_output() in an extra list literal:

return [self._parse_output(all_vectors)]   # wrong

Every other vector store returns the list directly:

return self._parse_output(all_vectors)     # correct

Fix

Remove the outer [...].

[biswajeetdev]

One-line fix, clearly correct. _parse_output returns a list, so wrapping it in [...] was producing a list-of-a-list — callers iterating over the result of list() would get a single element (the inner list) rather than the individual vectors.

Two small follow-up suggestions:

1. Test coverage — this is a silent data shape bug that is easy to reintroduce. A unit test asserting that list() returns a flat list of vector objects (not a nested list) would lock in the fix.

2. Parallel issue in other stores — worth a quick grep across the other vector store implementations (pinecone.py, chroma.py, etc.) to check if any have the same [self._parse_output(...)] pattern in their list() methods.