List owned brands

Return the calling workspace's own brand profiles — the entities you create under Atria's brand-management UI. Each carries the brand id, name, industries, logo, website, color palette and fonts.

Use the returned id as brand_id for the image generation endpoints. Distinct from GET /open/v1/brand-library/followed (catalog brands the workspace tracks) and GET /open/v1/brand-library/search (global ad-library catalog).

Returns: code=0 success; code=40001 workspace context missing.