fix(web): remove inert global autoMonitorFuture checkbox from Monitor tab

The worker never reads the global monitor.autoMonitorFuture Config key;
auto-monitor-future is governed solely by the per-artist
WatchedArtist.autoMonitorFuture toggle on the Artists page. Removes the
misleading no-op checkbox and its DEFAULTS/test entries.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/app/api/monitor/config/route.ts

@@ -2,7 +2,6 @@ import { prisma } from "@/lib/db";
 
 const DEFAULTS: Record<string, string> = {
   "monitor.enabled": "false",
-  "monitor.autoMonitorFuture": "false",
   "monitor.pollIntervalHours": "24",
   "monitor.retryIntervalHours": "6",
   "monitor.qualityCutoff": "2",