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]/monitoring/route.ts

@@ -1,3 +1,4 @@
+import { revalidatePath } from "next/cache";
 import { NextRequest, NextResponse } from "next/server";
 import { updateLibraryMonitoring } from "@/lib/api";
 
@@ -9,6 +10,7 @@ export async function PATCH(
   try {
     const { monitor_enabled, scan_mode, watcher_enabled, metadata_refresh_mode } = await request.json();
     const data = await updateLibraryMonitoring(id, monitor_enabled, scan_mode, watcher_enabled, metadata_refresh_mode);
+    revalidatePath("/libraries");
     return NextResponse.json(data);
   } catch (error) {
     const message = error instanceof Error ? error.message : "Failed to update monitoring settings";