Provider helper for custom chart i18n strings. Overrides merge over
the English defaults, so a consumer localises only the keys they
care about and every key added to CngxChartI18n later keeps
its default instead of forcing an update. Passing a full object
still works - it simply overrides every key.
providers: [provideChartI18n({ summary: ({ trend, min, max, current }) => `${trend === 'up' ? 'Aufwärtstrend' : 'Abwärtstrend'}. Min ${min}, Max ${max}, aktuell ${current}.`, dataTable: () => 'Datentabelle',})]