feat: separate sql

backend/app/sql/history.sql

@@ -0,0 +1,14 @@
+select
+    c.*,
+    a.title as listing_a_title,
+    b.title as listing_b_title,
+    w.title as winner_title
+from {elo_schema}.comparisons as c
+left join {listings_schema}.{listings_table} as a
+    on c.listing_a_id = a.global_id
+left join {listings_schema}.{listings_table} as b
+    on c.listing_b_id = b.global_id
+left join {listings_schema}.{listings_table} as w
+    on c.winner_id = w.global_id
+order by c.created_at desc
+limit :limit