Add a typed platform package to decouple the frontend from Tauri (#539)

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

apps/yaak-client/lib/settings.ts

@@ -1,6 +1,6 @@
-import { invoke } from "@tauri-apps/api/core";
 import type { Settings } from "@yaakapp-internal/models";
+import { rpc } from "./rpc";
 
 export function getSettings(): Promise<Settings> {
-  return invoke<Settings>("models_get_settings");
+  return rpc<Settings>("models_get_settings");
 }