fix(pixel): correct Geist Pixel copyright to reference geist-font (#237)

The source copyright pointed at a non-existent `vercel/geistpixel-font` repo
and didn't match OFL.txt. Align it with the rest of the family ("The Geist
Project Authors", https://github.com/vercel/geist-font) so the variable font
passes Google Fonts' fontspector copyright/OFL consistency checks ahead of
onboarding. Rebuilt GeistPixel[ELSH].ttf so the name table matches.

Author: christopherkindl

fonts/GeistPixel/variable/GeistPixel[ELSH].ttf

@@ -522,7 +522,7 @@ key = copyrights;
 values = (
 {
 language = dflt;
-value = "Copyright 2026 The Geist Pixel Project Authors (https://github.com/vercel/geistpixel-font.git)";
+value = "Copyright 2026 The Geist Project Authors (https://github.com/vercel/geist-font)";
 }
 );
 },