Limit the number of scores in the feed

The scores table can get big pretty fast, so as a performance measure, we should limit the number of scores returned for the feed.

Normally, we would add some pagination, but for now, let's just return the most recent 25 scores. Add a test for this.

Make sure `rubocop` and `rspec` pass.

查找取得 scores 的 feed endpoint 或 query，可能在 controller 或 service 檔案中。修改它，將結果限制為依建立日期排序的最新 25 筆 scores。在對應的 spec 檔案中撰寫一個 test，驗證該限制有效。執行 rubocop 和 rspec 以確保所有內容都通過。

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