ux: consider marking your order(s) in order book

[norwnd]

Would be nice to have visual indicator like so:

[norwnd]

I've sketched a solution for my own use here that works pretty well:

it's a bunch of changes packed into single commit (see the parts most relevant for this issue in markets.ts), feel free to borrow whatever code you want (if any).

[norwnd]

Actually it's better to use pure CSS for this - see this comment for details