Order Book Improvements

The order book is a little busy. It's not really wide enough to warrant striped rows. Let's remove those. Also, if we can give a reference to the depth chart here with significant markers, it may remove the need for the depth chart toggle. This allows the user to have more information without toggling. This is a rough start and intended to spark discussion. I also noticed that most charting systems only show the size of the order for one side of the market.

I.e., if we are on BTS/USD, everything is priced in USD.

## Notes
- [ ] Gray tick Call Limit
- [ ] Red Tick Settlement
- [ ] Yellow Tick Margin Call
- [ ] Bars are cumulative orders
- [ ] Hovering over each bar makes it a stronger version of that color and also lights up the corresponding value in the Exchange Header.
- [ ] Dark black background (hover state)
- [ ] Entire area scrolls (not separate scrolling areas for bid and ask)
- [ ] Only show order size (quantity) and price for one side of the market
- [ ] Decimals but all be in line
- [ ] Extra credit: dim gray for all insignificant leading and trailing zeros

Start by locating the order book and depth-chart UI entry points, then compare their current behavior with the screenshot and checklist. Done would require an agreed design covering row striping, significant markers, hover states, scrolling, displayed quantities and prices, decimal alignment, and the depth-chart toggle.

Written by the indexing model from the issue text.