Returns the filter options (categories, GMV ranges, follower segments, engagement / view tiers, content-style options, etc.) valid for the given shop region. Use the response to drive filter dropdowns or to validate creators_to_include.filters values before submitting a create request.

Region differences:

• Numeric ranges use the region's currency (£ for UK, $ for US, € for EU regions, R$ for BR, etc.).
• Category lists differ — UK has a smaller category set than US.
• AI-search filters (face_visibility / content_style / personality_tone / etc.) are only fully populated for US today; other regions surface a subset.
• Ethnicity filter is available globally regardless of region.

Supported regions: US, UK, IE, MX, DE, FR, ES, BR, IT, GLOBAL (alias for US).