Filter Seats based on their Price

This commit adds static HTML to render a set of <input type="radio"> buttons styled with <label> elements that wrap <svg> elements.

The values of those filters are static for the time being, and the selection of a filter does not yet affect the page. The values have been chosen as 500 cents ($5.00), 1000 cents ($10.00), and 1500 cents ($15.00). They’re underscored to resemble their price in dollars, and are iterated over with Array#each_cons to iterate over pairs consecutively.

Where there is a nil value for next_maximum, that indicates that it’s the highest possible value, so the <input> should have the checked attribute.

Desktop