writeCodepoint
Writes one Unicode scalar value at the cursor position using the active pen attributes, then advances the cursor.
This is the core fast path for simple printable text. It does not perform grapheme segmentation or merge combining marks into a previous cell; a parser/segmenter must dispatch pre-segmented grapheme clusters via writeCluster.
Wrapping, scrolling, and wide-character handling are applied automatically.
Parameters
codepoint
Unicode codepoint to write.