Refactor SQL queries to use parameterized values for player names and similarity percentage

service/data/diff.sql

@@ -4,14 +4,14 @@ with char1_achievements as (
 		date,
 		completed
 	from achievements
-	where name = 'Extazyk'
+	where name = $1
 ),
 char2_achievements as (
 	select id,
 		date,
 		completed
 	from achievements
-	where name = 'Smokemantra'
+	where name = $2
 ),
 all_achievements as (
 	select id