All views underwent similar changes:
• use dynamic colors instead of Theme. colors; as a result themeDidChange() is not longer needed.
• use system-provided layout margins for things like titles, subtitles and buttons.
• use standard "large primary", "large secondary" etc button styles instead of OWSButton and OWSFlatButton.
• use capsule shape for donation amount fields on iOS 26.
• make currency selection dropdown button a bit larger so that it looks better.
• other various layout code improvements.
