fix: Add unbounded context kind to segment type

[keelerm84]

Note

Low Risk
Low risk: adds an optional, defaulted field and tests, with no evaluation logic changes; primary risk is minor compatibility/serialization behavior changes for segment JSON.

Overview
Adds an optional unbounded_context_kind: Option<Kind> to Segment to deserialize the unboundedContextKind property for unbounded/big segments.

Adds unit tests to verify unboundedContextKind is parsed for both custom kinds (e.g. "org") and "user", and defaults to None when omitted; updates test segment construction accordingly.

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

New field is deserialized but never read

Low Severity

The unbounded_context_kind field is deserialized from JSON but never read in any production code. Unlike the similarly private generation field (which is consumed by unbounded_segment_id()), unbounded_context_kind has no accessor method and no internal usage. It's also not pub, so external crate consumers (e.g., big segment evaluation logic in the SDK layer) cannot access it either.

 

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[kinyoklion]

It will be used elsewhere.