perf(765-2): 벌 꺼내 끼우기 자식 행을 표마다 한 번에 넣음 — 칩 5.5~8 s → 약 2 s

- 검증_sub5 실측: _load_db 3.1~5.2 s(원격 DB 에 횡단 · 정점 줄마다 INSERT) → 0.5 s
- test_637_lidar 줄 길이 맞춤

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

common_util/common_util_design_sets.py

@@ -246,6 +246,19 @@ async def _insert(cursor: Any, table: str, row: dict[str, Any]) -> int:
     return int(cursor.lastrowid)
 
 
+async def _insert_many(cursor: Any, table: str, rows: list[dict[str, Any]]) -> None:
+    """한 표 여러 줄을 한 번에(원격 DB 왕복 줄 · 줄마다 넣으면 칩 5 s)."""
+    if not rows:
+        return
+    columns = list(rows[0])
+    names = ", ".join(f"`{name}`" for name in columns)
+    marks = ", ".join(["%s"] * len(columns))
+    await cursor.executemany(
+        f"INSERT INTO {table} ({names}) VALUES ({marks})",
+        [tuple(row.get(name) for name in columns) for row in rows],
+    )
+
+
 async def _load_db(
     connection: aiomysql.Connection, project_id: str, dump: dict[str, Any]
 ) -> dict[int, int]:
@@ -259,13 +272,15 @@ async def _load_db(
                 old = int(row.pop("id"))
                 route_map[old] = await _insert(cursor, "routes", row)
             for table in _ROUTE_CHILDREN:
+                rows = []
                 for child in dump.get(table, []):
                     row = dict(child)
                     row.pop("id", None)
                     row["route_id"] = route_map[int(row["route_id"])]
                     if "project_id" in row:
                         row["project_id"] = project_id
-                    await _insert(cursor, table, row)
+                    rows.append(row)
+                await _insert_many(cursor, table, rows)
             for stage in dump.get("stages", []):
                 sets = ", ".join(f"`{name}`=%s" for name in _STAGE_COLUMNS)
                 await cursor.execute(