Prompt glyphs and devicons previously depended on a locally installed
Nerd Font. The surface now vendors Symbols Nerd Font Mono (MIT, 1.2MB
woff2) and registers it through the FontFace API when the first
terminal mounts — lazy, cached, and awaited before cell metrics. The
face carries no regular text glyphs, so it composes with the default
stack and any future user-chosen face without affecting metrics.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>