Chart theming: user font upload (FontFace-from-IndexedDB) + variable-font weight support

src/app/services/transfer.ts

@@ -60,6 +60,10 @@ export function exportWorkspace(now: Date = new Date()): void {
     return;
   }
 
+  // TODO(fonts §08): the envelope does not yet carry user-uploaded FontAsset
+  // bytes, so a theme/snippet referencing an uploaded font imports on another
+  // machine with the fallback family. Embed the referenced faces (base64) here —
+  // best done with task #3's shared font-bytes→embeddable-string helper.
   const envelope = buildExportEnvelope(snippets, datasets, themes, { now });
   downloadJson(exportFilename(now), JSON.stringify(envelope, null, 2));