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/settings/settings-form.tsx

@@ -278,16 +278,6 @@ export function SettingsForm() {
               Automatic monitoring (grab & upgrade)
             </label>
           </div>
-          <div className="save-row" style={{ margin: "2px 0 8px" }}>
-            <label className="toggle">
-              <input
-                type="checkbox"
-                checked={monitorCfg["monitor.autoMonitorFuture"] === "true"}
-                onChange={(e) => setMon("monitor.autoMonitorFuture", e.target.checked ? "true" : "false")}
-              />
-              Auto-monitor future releases from watched artists
-            </label>
-          </div>
           <div className="field-grid">
             {MONITOR_FIELDS.map(([key, label]) => (
               <label key={key} className="field">