fix: revalidate /libraries cache after settings updates

Add revalidatePath("/libraries") to the monitoring, metadata-provider
and reading-status-provider route handlers so that saving library
settings invalidates the Next.js data cache and the page reflects
fresh data on reload.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/backoffice/app/api/libraries/[id]/reading-status-provider/route.ts

@@ -1,3 +1,4 @@
+import { revalidatePath } from "next/cache";
 import { NextResponse } from "next/server";
 import { apiFetch } from "@/lib/api";
 
@@ -13,6 +14,7 @@ export async function PATCH(
       headers: { "Content-Type": "application/json" },
       body: JSON.stringify(body),
     });
+    revalidatePath("/libraries");
     return NextResponse.json(data);
   } catch (error) {
     const message = error instanceof Error ? error.message : "Failed to update reading status provider";