Update achievement schema (#3542)

## Description:

Update the schema for achievements

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

evan

src/client/SinglePlayerModal.ts

@@ -144,14 +144,7 @@ export class SinglePlayerModal extends BaseModal {
       return;
     }
 
-    const achievements = Array.isArray(userMe.player.achievements)
+    const completions = userMe.player.achievements.singleplayerMap;
-      ? userMe.player.achievements
-      : [];
-
-    const completions =
-      achievements.find(
-        (achievement) => achievement?.type === "singleplayer-map",
-      )?.data ?? [];
 
     const winsMap = new Map<GameMapType, Set<Difficulty>>();
     for (const entry of completions) {

src/core/ApiSchemas.ts

@@ -56,14 +56,9 @@ export const UserMeResponseSchema = z.object({
     publicId: z.string(),
     roles: z.string().array().optional(),
     flares: z.string().array().optional(),
-    achievements: z
+    achievements: z.object({
-      .array(
+      singleplayerMap: z.array(SingleplayerMapAchievementSchema),
-        z.object({
+    }),
-          type: z.literal("singleplayer-map"), // TODO: change the shape to be more flexible when we have more achievements
-          data: z.array(SingleplayerMapAchievementSchema),
-        }),
-      )
-      .optional(),
     leaderboard: z
       .object({
         oneVone: z