refactor(desktop): organize lib modules by domain

apps/desktop/src/lib/document/documentViewerFontStyle.ts

@@ -0,0 +1,11 @@
+import { EDITOR_FONT_FAMILY_CSS_VAR, EDITOR_FONT_SIZE_CSS_VAR } from "@/lib/editor/editorThemes";
+import type { EditorSettings } from "@/stores/settingsStore";
+
+export type DocumentViewerFontSettings = Pick<EditorSettings, "fontFamily" | "fontSize">;
+
+export function documentViewerFontStyle(settings: DocumentViewerFontSettings): Record<string, string> {
+  return {
+    [EDITOR_FONT_FAMILY_CSS_VAR]: settings.fontFamily,
+    [EDITOR_FONT_SIZE_CSS_VAR]: `${settings.fontSize}px`,
+  };
+}