fix(prediction): 선박 항적 API URL 및 엔드포인트 수정

- VESSEL_TRACK_API_URL 기본값을 프로덕션 URL로 변경
  (localhost:9090 → https://guide.gc-si.dev/signal-batch)
- 항적 조회 API 경로 추가 (/api/v2/tracks/area-search)

backend/src/prediction/backtrackAnalysisService.ts

@@ -2,7 +2,7 @@ import { wingPool } from '../db/wingDb.js';
 import { getBacktrack } from './predictionService.js';
 
 const PYTHON_API_URL = process.env.PYTHON_API_URL ?? 'http://localhost:5003';
-const VESSEL_TRACK_API_URL = process.env.VESSEL_TRACK_API_URL ?? 'http://localhost:9090';
+const VESSEL_TRACK_API_URL = process.env.VESSEL_TRACK_API_URL ?? 'https://guide.gc-si.dev/signal-batch';
 
 // 유종 코드(DB) → OpenDrift 유종 코드 매핑
 const OIL_TYPE_MAP: Record<string, string> = {
@@ -288,7 +288,7 @@ async function fetchVesselTracks(
 
   console.log(body);
 
-  const res = await fetch(`${VESSEL_TRACK_API_URL}`, {
+  const res = await fetch(`${VESSEL_TRACK_API_URL}/api/v2/tracks/area-search`, {
     method: 'POST',
     headers: { 'Content-Type': 'application/json' },
     body: JSON.stringify(body),