Adds one or more columns to an existing audience in a single bulk operation. Columns define the data fields available for each row in the audience; each column has a name, a dataType (e.g., TEXT, INTEGER, EMAIL, DATE, BOOLEAN), and behavior flags (isFrozen, isHidden).

Supported column types:

• CUSTOM (columnType: CUSTOM) - Static user-provided values
• FORMULA (columnType: FORMULA) - Values generated from a formula prompt
• AI (columnType: AI) - AI-generated values with optional tool and dataDependencies context
• ZOOMINFO_MATCH (columnType: ZOOMINFO_MATCH) - Enrichment-driven values (configure via Upsert Column Match Criteria endpoint)

Returns 201 Created with the full array of created column resources including system-assigned columnId values and read-only flags. Returns 400 if required fields are missing or dataType is invalid. Returns 404 if no audience matches the provided audienceId.