Add MKT opt-in on threat intercept, jittered market fetches, and Sentinel multi-scene dossier.

Operators enable Polymarket/Kalshi correlation from Global Threat Intercept with a consent dialog; polls use a jittered schedule separate from the slow tier. Right-click Sentinel imagery returns up to three signed scenes again.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/hooks/usePredictionMarketsOptIn.ts

@@ -0,0 +1,54 @@
+'use client';
+
+import { useCallback, useEffect, useState } from 'react';
+import { API_BASE } from '@/lib/api';
+
+export type PredictionMarketsStatus = {
+  enabled: boolean;
+  ui_opted_in: boolean;
+  env_override: 'on' | 'off' | null;
+  jitter?: {
+    scheduler_interval_minutes: number;
+    scheduler_jitter_seconds: number;
+    pre_fetch_jitter_seconds: number;
+  };
+};
+
+export function usePredictionMarketsOptIn(enabled = true) {
+  const [status, setStatus] = useState<PredictionMarketsStatus | null>(null);
+
+  const refreshStatus = useCallback(async () => {
+    try {
+      const res = await fetch(`${API_BASE}/api/prediction-markets/status`);
+      if (!res.ok) return;
+      const body = (await res.json()) as PredictionMarketsStatus;
+      setStatus(body);
+    } catch {
+      // Backend may still be starting.
+    }
+  }, []);
+
+  useEffect(() => {
+    if (!enabled) return;
+    void refreshStatus();
+  }, [enabled, refreshStatus]);
+
+  const setOptIn = useCallback(
+    async (optedIn: boolean) => {
+      const res = await fetch(`${API_BASE}/api/prediction-markets/opt-in`, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ opted_in: optedIn }),
+      });
+      if (!res.ok) {
+        throw new Error(`Prediction markets opt-in failed (${res.status})`);
+      }
+      const body = (await res.json()) as PredictionMarketsStatus;
+      setStatus(body);
+      return body;
+    },
+    [],
+  );
+
+  return { status, refreshStatus, setOptIn };
+}