Preview spreadsheet segmentation distributions

Enterprise review step for grounded audience creation. Classifies respondent-level XLS/XLSX/CSV/SPSS-SAV fields by research role, selects population and segmentation variables while holding outcomes and drivers out, and discovers privacy-safe pairwise relationships. Questionnaire/programming grids are rejected as design evidence instead of being misrepresented as completed respondents. Joint profiles are counted for audit only; rows are never silently sampled. An SPSS .sav is read with its codebook, so value labels, not codes, are reported and declared missing codes count as non-response.