Fields per customer as key-value pairs. Keys are field names declared in the application configuration (custom fields or default system fields).

Default system fields (field_role mapped):

• email (string): Customer email address

• phone (string): Customer phone number without country prefix (e.g. "603174460")

• phoneE164 (string): Customer phone in E.164 format — includes country prefix (e.g. "+34603174460").
  Recommended when the full international number is available, as it allows channel services to
  derive both the national number and the country code automatically.

• country_code (string): Country calling code digits only (e.g. "34")

• name (string): Customer full name

• birthday (datetime): Customer birth date (ISO 8601)

• language (string): Customer preferred language (ISO 639-1)

Boolean fields: values for boolean fields are normalized before being stored, so the following representations are accepted and converted to a real boolean: true/false (boolean), "true"/"false" (string, case-insensitive) and 1/0 (as number or string). The boolean value false is a real value and does not delete the field — only "" or null delete it.