feat(korea): 임검침로 해상 루트 — 육지 우회 경유점 자동 삽입

- 한반도 해안 웨이포인트 14개 정의 (서해→남해→동해 시계방향)
- 육지 바운딩박스 2개 (본토 + 제주도)
- 직선이 육지 관통 시 해안 경유점 자동 삽입
- 시계/반시계 경로 중 짧은 쪽 자동 선택
- 직선 통과 가능 시 그대로 직선 유지

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

frontend/src/components/korea/KoreaMap.tsx

@@ -104,6 +104,93 @@ const MAP_STYLE = {
   ],
 };
 
+// ═══ Sea routing — avoid Korean peninsula land mass ═══
+// Coastal waypoints around Korea (clockwise from NW)
+const SEA_WAYPOINTS: [number, number][] = [
+  [124.5, 37.8],  // 서해 북부 (백령도 서)
+  [124.0, 36.5],  // 서해 중부
+  [124.5, 35.5],  // 서해 남부
+  [125.0, 34.5],  // 서남해 (신안)
+  [126.0, 33.5],  // 남해 서단 (제주 서)
+  [126.5, 33.2],  // 제주 남서
+  [127.5, 33.0],  // 제주 남
+  [128.5, 33.5],  // 제주 동
+  [129.0, 34.5],  // 남해 동단 (거제)
+  [129.5, 35.2],  // 부산 남
+  [129.8, 36.0],  // 동해 남부 (울산)
+  [130.0, 37.0],  // 동해 중부
+  [129.5, 37.8],  // 동해 북부 (강릉)
+  [129.0, 38.5],  // 동해 최북
+];
+
+// Simplified land bounding boxes for Korean peninsula
+const LAND_BOXES: { minLng: number; maxLng: number; minLat: number; maxLat: number }[] = [
+  { minLng: 125.5, maxLng: 129.5, minLat: 34.3, maxLat: 38.6 }, // 한반도 본토
+  { minLng: 126.1, maxLng: 126.9, minLat: 33.2, maxLat: 33.6 }, // 제주도
+];
+
+function segmentCrossesLand(lng1: number, lat1: number, lng2: number, lat2: number): boolean {
+  const steps = 10;
+  for (let i = 1; i < steps; i++) {
+    const t = i / steps;
+    const lng = lng1 + (lng2 - lng1) * t;
+    const lat = lat1 + (lat2 - lat1) * t;
+    for (const box of LAND_BOXES) {
+      if (lng >= box.minLng && lng <= box.maxLng && lat >= box.minLat && lat <= box.maxLat) return true;
+    }
+  }
+  return false;
+}
+
+function nearestWaypoint(lng: number, lat: number): number {
+  let bestIdx = 0, bestDist = Infinity;
+  for (let i = 0; i < SEA_WAYPOINTS.length; i++) {
+    const d = (SEA_WAYPOINTS[i][0] - lng) ** 2 + (SEA_WAYPOINTS[i][1] - lat) ** 2;
+    if (d < bestDist) { bestDist = d; bestIdx = i; }
+  }
+  return bestIdx;
+}
+
+function buildSeaRoute(from: { lat: number; lng: number }, to: { lat: number; lng: number }): [number, number][] {
+  // Direct line doesn't cross land → straight route
+  if (!segmentCrossesLand(from.lng, from.lat, to.lng, to.lat)) {
+    return [[from.lng, from.lat], [to.lng, to.lat]];
+  }
+
+  // Find nearest waypoints for start and end
+  const startWP = nearestWaypoint(from.lng, from.lat);
+  const endWP = nearestWaypoint(to.lng, to.lat);
+
+  // Build path through coastal waypoints (shortest direction)
+  const n = SEA_WAYPOINTS.length;
+  const cwPath: [number, number][] = [];
+  const ccwPath: [number, number][] = [];
+
+  // Clockwise
+  for (let i = startWP; ; i = (i + 1) % n) {
+    cwPath.push(SEA_WAYPOINTS[i]);
+    if (i === endWP) break;
+    if (cwPath.length > n) break; // safety
+  }
+
+  // Counter-clockwise
+  for (let i = startWP; ; i = (i - 1 + n) % n) {
+    ccwPath.push(SEA_WAYPOINTS[i]);
+    if (i === endWP) break;
+    if (ccwPath.length > n) break;
+  }
+
+  const waypoints = cwPath.length <= ccwPath.length ? cwPath : ccwPath;
+
+  // Filter waypoints that are actually between from and to (remove unnecessary detours)
+  const filtered = waypoints.filter(wp => {
+    // Keep waypoint if removing it would cross land
+    return true; // keep all for safety
+  });
+
+  return [[from.lng, from.lat], ...filtered, [to.lng, to.lat]];
+}
+
 // Korea-centered view
 const KOREA_MAP_CENTER = { longitude: 127.5, latitude: 36 };
 const KOREA_MAP_ZOOM = 6;
@@ -944,23 +1031,20 @@ export function KoreaMap({ ships, allShips, aircraft, satellites, layers, osintF
         />
       )}
 
-      {/* 작전가이드 임검침로 점선 */}
+      {/* 작전가이드 임검침로 점선 — 해상 루트 (육지 우회) */}
       {opsRoute && (() => {
         const riskColor = opsRoute.riskLevel === 'CRITICAL' ? '#ef4444' : opsRoute.riskLevel === 'HIGH' ? '#f59e0b' : '#3b82f6';
+        const coords = buildSeaRoute(opsRoute.from, opsRoute.to);
         const routeGeoJson: GeoJSON.FeatureCollection = {
           type: 'FeatureCollection',
           features: [{
-            type: 'Feature',
-            properties: {},
-            geometry: {
-              type: 'LineString',
-              coordinates: [
-                [opsRoute.from.lng, opsRoute.from.lat],
-                [opsRoute.to.lng, opsRoute.to.lat],
-              ],
-            },
+            type: 'Feature', properties: {},
+            geometry: { type: 'LineString', coordinates: coords },
           }],
         };
+        const midIdx = Math.floor(coords.length / 2);
+        const midLng = coords[midIdx][0];
+        const midLat = coords[midIdx][1];
         return (
           <>
             <Source id="ops-route-line" type="geojson" data={routeGeoJson}>
@@ -981,11 +1065,7 @@ export function KoreaMap({ ships, allShips, aircraft, satellites, layers, osintF
                 boxShadow: `0 0 8px ${riskColor}`,
               }} />
             </Marker>
-            <Marker
-              longitude={(opsRoute.from.lng + opsRoute.to.lng) / 2}
-              latitude={(opsRoute.from.lat + opsRoute.to.lat) / 2}
-              anchor="bottom"
-            >
+            <Marker longitude={midLng} latitude={midLat} anchor="bottom">
               <div style={{
                 background: 'rgba(0,0,0,0.8)', padding: '2px 6px', borderRadius: 3,
                 border: `1px solid ${riskColor}`, fontSize: 9, color: '#fff', fontWeight: 700,