fix(api): fix api endpoint logic #5

chore(env): obscure api url in env

feat(ui): render subjects according to user preparation unit

app/(tabs)/layout.tsx

@@ -9,7 +9,7 @@ import { House, LayoutGrid, Bookmark, Settings } from "lucide-react";
 
 const tabs = [
   { name: "Home", href: "/home", component: <House size={30} /> },
-  { name: "Unit", href: "/unit", component: <LayoutGrid size={30} /> },
+  { name: "Subjects", href: "/subjects", component: <LayoutGrid size={30} /> },
   { name: "Bookmark", href: "/bookmark", component: <Bookmark size={30} /> },
   { name: "Settings", href: "/settings", component: <Settings size={30} /> },
 ];