Add auth guards to search and discover API routes

app/api/explore/discover/route.ts

@@ -1,9 +1,18 @@
+import { headers } from "next/headers";
 import { type NextRequest, NextResponse } from "next/server";
+import { auth } from "@/lib/auth/server";
 import { isTmdbConfigured } from "@/lib/config";
 import { discover } from "@/lib/tmdb/client";
 import { tmdbImageUrl } from "@/lib/tmdb/image";
 
 export async function GET(req: NextRequest) {
+  const session = await auth.api.getSession({
+    headers: await headers(),
+  });
+  if (!session) {
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+  }
+
   if (!isTmdbConfigured()) {
     return NextResponse.json(
       {