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.test.ts

@@ -12,7 +12,7 @@ describe("monitor config API", () => {
   it("GET returns defaults when nothing is stored", async () => {
     const body = await (await GET()).json();
     expect(body).toMatchObject({
-      "monitor.enabled": "false", "monitor.autoMonitorFuture": "false",
+      "monitor.enabled": "false",
       "monitor.pollIntervalHours": "24", "monitor.retryIntervalHours": "6",
       "monitor.qualityCutoff": "2", "monitor.upgradeWindowDays": "14",
     });