feat: 선택 어구그룹 하이라이트 폴리곤 + 모선 강조 마커

- 선택된 어구그룹: 진한 주황 fill(0.25) + 굵은 경계선(3px)
- 모선 존재 시: 28px 주황 원 + glow + 'M' 라벨 + 선박명
- zoom 시 자동 선택 + 펼침

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/korea/FleetClusterLayer.tsx

@@ -1,5 +1,5 @@
 import { useState, useEffect, useMemo, useCallback } from 'react';
-import { Source, Layer } from 'react-map-gl/maplibre';
+import { Source, Layer, Marker } from 'react-map-gl/maplibre';
 import type { GeoJSON } from 'geojson';
 import type { Ship, VesselAnalysisDto } from '../../types';
 import { fetchFleetCompanies } from '../../services/vesselAnalysis';
@@ -89,6 +89,7 @@ export function FleetClusterLayer({ ships, analysisMap, clusters, onShipSelect,
   const [expandedFleet, setExpandedFleet] = useState<number | null>(null);
   const [hoveredFleetId, setHoveredFleetId] = useState<number | null>(null);
   const [expandedGearGroup, setExpandedGearGroup] = useState<string | null>(null);
+  const [selectedGearGroup, setSelectedGearGroup] = useState<string | null>(null);
 
   useEffect(() => {
     fetchFleetCompanies().then(setCompanies).catch(() => {});
@@ -199,6 +200,8 @@ export function FleetClusterLayer({ ships, analysisMap, clusters, onShipSelect,
   }, [gearGroupMap]);
 
   const handleGearGroupZoom = useCallback((parentName: string) => {
+    setSelectedGearGroup(prev => prev === parentName ? null : parentName);
+    setExpandedGearGroup(parentName);
     const entry = gearGroupMap.get(parentName);
     if (!entry) return;
     const all: Ship[] = [...entry.gears];
@@ -383,6 +386,60 @@ export function FleetClusterLayer({ ships, analysisMap, clusters, onShipSelect,
         />
       </Source>
 
+      {/* 선택된 어구 그룹 하이라이트 + 모선 마커 */}
+      {selectedGearGroup && (() => {
+        const entry = gearGroupMap.get(selectedGearGroup);
+        if (!entry) return null;
+        const points: [number, number][] = entry.gears.map(g => [g.lng, g.lat]);
+        if (entry.parent) points.push([entry.parent.lng, entry.parent.lat]);
+
+        const hlFeatures: GeoJSON.Feature[] = [];
+        if (points.length >= 3) {
+          const hull = convexHull(points);
+          const padded = padPolygon(hull, 0.01);
+          padded.push(padded[0]);
+          hlFeatures.push({
+            type: 'Feature',
+            properties: {},
+            geometry: { type: 'Polygon', coordinates: [padded] },
+          });
+        }
+        const hlGeoJson: GeoJSON.FeatureCollection = { type: 'FeatureCollection', features: hlFeatures };
+
+        return (
+          <>
+            {hlFeatures.length > 0 && (
+              <Source id="gear-cluster-selected" type="geojson" data={hlGeoJson}>
+                <Layer id="gear-selected-fill" type="fill" paint={{ 'fill-color': '#f97316', 'fill-opacity': 0.25 }} />
+                <Layer id="gear-selected-line" type="line" paint={{ 'line-color': '#f97316', 'line-width': 3, 'line-opacity': 0.9 }} />
+              </Source>
+            )}
+            {entry.parent && (
+              <Marker longitude={entry.parent.lng} latitude={entry.parent.lat} anchor="center">
+                <div style={{
+                  width: 28, height: 28, borderRadius: '50%',
+                  border: '3px solid #f97316',
+                  backgroundColor: 'rgba(249, 115, 22, 0.3)',
+                  boxShadow: '0 0 12px rgba(249, 115, 22, 0.6)',
+                  display: 'flex', alignItems: 'center', justifyContent: 'center',
+                  pointerEvents: 'none',
+                }}>
+                  <span style={{ fontSize: 9, fontWeight: 900, color: '#fff' }}>M</span>
+                </div>
+                <div style={{
+                  fontSize: 8, fontWeight: 700, color: '#f97316',
+                  textShadow: '0 0 3px #000, 0 0 3px #000',
+                  textAlign: 'center', marginTop: 2, whiteSpace: 'nowrap',
+                  pointerEvents: 'none',
+                }}>
+                  {entry.parent.name || entry.parent.mmsi}
+                </div>
+              </Marker>
+            )}
+          </>
+        );
+      })()}
+
       {/* 비허가 어구 클러스터 폴리곤 */}
       <Source id="gear-clusters" type="geojson" data={gearClusterGeoJson}>
         <Layer