feat: improve SQL query formatting and add type hints for better clarity

scripts/benchmark_metrics_compute.py

@@ -13,13 +13,11 @@ from arbitrade.storage.db import DuckDBStore
 
 def _python_scan_compute(store: DuckDBStore) -> tuple[float, float | None, float | None]:
     with store.connect() as conn:
-        trade_rows = conn.execute(
-            """
+        trade_rows = conn.execute("""
             SELECT started_at, finished_at, realized_pnl
             FROM trades
             WHERE finished_at IS NOT NULL
-            """
-        ).fetchall()
+            """).fetchall()
         opportunity_rows = conn.execute("SELECT detected_at FROM opportunities").fetchall()
 
     realized = sum(float(row[2]) for row in trade_rows if row[2] is not None)