fix(music-lab): trend report list에 top_genres/recommended_styles 포함

GET /api/music/market/report 응답에 top_genres, recommended_styles를 포함해
히스토리 리포트 클릭 시 장르 차트와 Suno 프롬프트가 비어 보이는 버그 수정.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

music-lab/app/db.py

@@ -694,9 +694,16 @@ def get_latest_trend_report() -> Optional[Dict[str, Any]]:
 def get_trend_reports(limit: int = 10) -> list:
     with _conn() as conn:
         rows = conn.execute(
-            "SELECT id, report_date, insights, created_at FROM trend_reports "
-            "ORDER BY report_date DESC LIMIT ?", (limit,)
+            "SELECT * FROM trend_reports ORDER BY report_date DESC LIMIT ?", (limit,)
         ).fetchall()
-    return [{"id": r["id"], "report_date": r["report_date"],
-             "insights": r["insights"][:100], "created_at": r["created_at"]}
-            for r in rows]
+    return [
+        {
+            "id":                 r["id"],
+            "report_date":        r["report_date"],
+            "top_genres":         json.loads(r["top_genres"] or "[]"),
+            "recommended_styles": json.loads(r["recommended_styles"] or "[]"),
+            "insights":           (r["insights"] or "")[:100],
+            "created_at":         r["created_at"],
+        }
+        for r in rows
+    ]