Use adfree flag to suppress ads

Adds adfree: boolean to player in UserMeResponseSchema and replaces the flares-length heuristic in Main.ts with a direct check of this field to determine whether ads should be shown.

src/core/ApiSchemas.ts

@@ -77,6 +77,7 @@ export const UserMeResponseSchema = z.object({
   }),
   player: z.object({
     publicId: z.string(),
+    adfree: z.boolean(),
     flares: z.string().array().optional(),
     achievements: z.object({
       singleplayerMap: z.array(SingleplayerMapAchievementSchema),