Results feature polish: badges, contrast, Avg/Best separation

The Results feature could use some UI polish for readability and quick scanning.

## Todo
- Add PR / NR / WR badges
- Fix color contrast (especially in dark mode)
- Make the Avg and Best columns more visually distinct
- ideas: wider cells, a vertical separator line between solve times and Avg/Best, or stronger header styling

## Notes
- Goal: make it easier to scan results at a glance without losing legibility in dark mode.

先定位 Results 功能的 UI 入口與現有樣式，接著檢視結果表格在淺色與深色模式下的呈現。完成標準是 PR、NR 與 WR 徽章均已顯示、深色模式下的對比度清晰易讀，且 Avg 與 Best 欄位在不降低可讀性的情況下具有明顯的視覺區隔。

由索引模型根據 Issue 內容生成。