Fix desktop showing the mobile layout: decide layout from the actual build platform (cfg!(mobile)) instead of sniffing the webview user-agent, which some WebKitGTK builds report mobile-looking (#63)

src/lib/api.ts

@@ -463,6 +463,10 @@ export async function getInstallType(): Promise<string> {
   return invoke("get_install_type");
 }
 
+export async function isMobilePlatform(): Promise<boolean> {
+  return invoke("is_mobile_platform");
+}
+
 export async function getPendingOpenFile(): Promise<string | null> {
   return invoke("get_pending_open_file");
 }