Context Studio: no way to add or edit labels on transcripts

Summary

The Context Studio UI displays a label field on transcripts in both the table view and the sidecar detail panel, but there is no input, dropdown, or control to actually create, assign, or edit labels. The field is read-only with no way to populate it.

Expected behavior

Users should be able to create and assign labels to transcripts from within Context Studio -- either inline in the table, in the sidecar, or via a dedicated control.

Current behavior

Labels appear as a column/field but are always empty and non-interactive. There is no affordance to add or manage them.

Why it matters

Labels are the natural way to organize and filter transcripts (e.g., by feature area, project, or workflow stage). Without the ability to set them, the field is dead UI that suggests missing functionality.