Malayalam graphemes render at incorrect cell positions #1401

Description

Malayalam grapheme clusters can render at incorrect horizontal positions in static text. In the observed case, the final glyphs appeared near or beyond the right edge of the containing panel instead of remaining contiguous with the rest of the title.

The exact string was:

OpenCode search configuration പരിശോധിക്കൽ

This was rendered in an OpenCode session tab using a fixed-width <text> with wrapMode="none". The title was not being scrolled.

Expected

The Malayalam word renders contiguously after the ASCII prefix and remains within the text bounds.

Actual

Parts of the Malayalam word render as separated glyphs at incorrect cell positions, including near the right edge of the panel.

Environment

• OpenTUI: 0.5.6
• Terminal: Ghostty 1.3.1
• OS: macOS 25.5.0 (arm64)
• Consumer: OpenCode 0.0.0-beta-17728

This may share a root cause with #479, but that report concerns corruption while scrolling Thai text. This reproduction is static Malayalam text on a newer OpenTUI version.