Minor Update - UI Improvements

[p]Quick-Buy hotkeys changed: 1~6 → Ins / Home / PgUp / Del / End / PgDn (right-hand keys for easier access during combat)[/p]
[p]Quick-Buy slot layout changed to 2×3 grid, repositioned next to HP bar[/p]
[p]Fixed buff icon (octopus) briefly appearing on hit[/p]
[p]Cleaned up unused UI elements[/p]
[p]Buff display icons unified in size[/p]