Type guard to validate if a value is a valid availability status.
Checks if the value is a string that matches one of the predefined AVAILABILITY enum values.
Matching is case-insensitive — input is lowercased before comparison.
Type guard to validate if a value is a valid product variant.
Checks for the presence and correct types of variant properties.
A variant can be partial as it may inherit some properties from the parent product
(such as uom, currency, URL, etc.).
Type guard to validate if a value is a valid availability status. Checks if the value is a string that matches one of the predefined AVAILABILITY enum values. Matching is case-insensitive — input is lowercased before comparison.