The same clean layout on every page

Every app page now follows the same layout, so nothing jumps around as you move between charts.

What changed

• Same spacing everywhere. Legends and chart cards line up the same way on charts, heatmeters, the calendar and the derivatives pages.
• Loading screens that match the page. Spinners and blank screens are replaced by placeholders in the shape of the page, so it doesn't shift when the data arrives.
• Risk Rotation now has the same chart header as the other charts.
• Favorites and Tutorials use the standard dark layout.
• Dow Jones: the duplicate page now forwards to the main one, so old links keep working.