fix logo parsing cutoff and asahi remix colors

Logo header detection was incorrectly matching logo content lines
ending in ':' (e.g. macOS, Windows, Fedora logos). Now requires
headers to start with a letter and be under 40 chars.

Updated fedora-asahi-remix colors to actual Asahi Linux branding
(pink #d3506f / teal #00a67c) using true color escape codes.