firstCodePointOrNull
The first Unicode code point in this string, combining a surrogate pair into the single value it encodes.
The multiplatform counterpart to String.codePointAt(0), which is JVM-only: reading this[0].code instead would return a lone high surrogate for every emoji outside the basic plane, and a waypoint icon is usually exactly that. Returns null for an empty string rather than throwing, since the caller is handling user-picked text.