Shop configuration storage schema (key-value JSONB).

Used for storing global Shop module settings like:

• global_attribute_schema - Global product attribute definitions

Attribute Schema Format

%{
  "key" => "material",
  "label" => "Material",
  "type" => "select",
  "options" => ["PLA", "ABS", "PETG"],
  "default" => "PLA",
  "required" => false,
  "unit" => nil,
  "position" => 0
}

Supported types: text, number, boolean, select, multiselect