feat: add Fixel font support

Adds Fixel Text as a new UI font option
Allows font sources to load from direct URLs
Keeps existing fontsource-based loading working

packages/ui/src/lib/fontLoader.ts

@@ -4,6 +4,10 @@ const loadedFaces = new Set<string>();
 const pendingFaces = new Map<string, Promise<void>>();
 
 const buildFontUrl = (source: FontFaceSource, weight: number) => {
+  if ('urls' in source) {
+    return source.urls[weight];
+  }
+
   const packageName = encodeURIComponent(source.packageName).replace('%40', '@').replace('%2F', '/');
   return `https://cdn.jsdelivr.net/npm/${packageName}/files/${source.filePrefix}-latin-${weight}-normal.woff2`;
 };