History page UI improvements

We have made a few visual improvements to the History page to make trade review feel cleaner and easier to scan.

What changed

Updated the CSV export button with a cleaner blue button style and a download icon.

Redesigned paired BUY and SELL history cards into a clearer trade lifecycle layout.

Made trade entries easier to scan with entry, exit, result, fees, hold time, size, and exit reason shown more clearly.

Improved the look and structure of open trades so they no longer feel like incomplete BUY/SELL cards.

These changes are focused on making trade history easier to understand at a glance while keeping the same underlying trade data.