feat(threat-actors): hover tooltip on motivation badges

New MotivationBadge component with CSS tooltip showing:
- espionage: goal (intelligence theft), typical behavior, examples
- financial: goal (monetary), typical behavior, examples
- destruction: goal (disrupt/destroy infra), wiper/ICS attacks, examples
- hacktivism: goal (political/ideological), defacement/leaks, examples

Used in ThreatActorsPage (card list) and ThreatActorDetailPage (header).

frontend/src/pages/ThreatActorDetailPage.tsx

@@ -1,5 +1,6 @@
 import { useParams, useNavigate } from "react-router-dom";
 import MarkdownText from "../components/MarkdownText";
+import MotivationBadge from "../components/MotivationBadge";
 import { useQuery } from "@tanstack/react-query";
 import {
   Loader2,
@@ -218,10 +219,7 @@ export default function ThreatActorDetailPage() {
             </span>
           )}
           {actor.motivation && (
-            <span className="inline-flex items-center gap-1.5 rounded-full border border-purple-500/30 bg-purple-900/50 px-3 py-1 text-xs text-purple-400">
-              <Target className="h-3.5 w-3.5" />
-              {actor.motivation}
-            </span>
+            <MotivationBadge motivation={actor.motivation} />
           )}
           {actor.sophistication && (
             <span className="inline-flex items-center gap-1.5 rounded-full border border-cyan-500/30 bg-cyan-900/50 px-3 py-1 text-xs text-cyan-400">