Aggregate's hybrid search is missing fusionType, unlike Get's hybrid

Describe your feature request

Get{ClassName}(hybrid: {...}) exposes a fusionType argument to choose between rankedFusion (legacy) and relativeScoreFusion — see adapters/handlers/graphql/local/get/hybrid_search.go:70-73.

Aggregate{ClassName}(hybrid: {...})'s equivalent input object has no fusionType field (adapters/handlers/graphql/local/aggregate/hybrid_search.go:49-114), so Aggregate hybrid queries are silently locked to the default fusion algorithm (HybridRelativeScoreFusion) with no way to select rankedFusion.

This isn't a case of the underlying logic not supporting it — both Get and Aggregate already route through the same shared ExtractHybridSearch function (adapters/handlers/graphql/local/common_filters/hybrid.go:136-141), which already reads and applies fusionType whenever it's present in the input map. The capability exists end-to-end; it's just missing from Aggregate's GraphQL schema.

Happy to open a PR — I have a working implementation adding the field to Aggregate's schema and confirming (via new resolver-level tests) that both rankedFusion and relativeScoreFusion now correctly propagate through to aggregation.Params.

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