[BUG] Aggregate API responses always contain empty dict for `available_pipelines`

Is there an existing issue for this?

[x] I have searched the existing issues

Expected Behavior

When subject data in the graph contains pipeline metadata, an aggregate mode query response for the dataset should include a non-empty dictionary for available_pipelines.

Current Behavior

available_pipelines is always an empty dictionary {}.

This is because the aggregation statement in the SPARQL query template has not yet been updated to return pipeline variables, and similarly, the API-side handling of the graph response for an aggregate query currently does not consider these variables. https://github.com/neurobagel/api/blob/c150b37c659ffd16fe3d38d982f09ccd5edf996c/app/api/utility.py#L306-L315

At the same time, the value of available_pipelines is always initialized as an empty dict: https://github.com/neurobagel/api/blob/c150b37c659ffd16fe3d38d982f09ccd5edf996c/app/api/crud.py#L171 https://github.com/neurobagel/api/blob/c150b37c659ffd16fe3d38d982f09ccd5edf996c/app/api/crud.py#L290

And so this is what is currently always returned in aggregate mode.

Error message

No response

Environment

OS:
Python/Node version:

How to reproduce

Install and launch the API from source, in aggregate mode, and point it to a graph containing data from fhttps://github.com/neurobagel/neurobagel_examples/tree/main/data-upload/pheno-bids-derivatives-output.

Anything else?

No response

neurobagel / api