This PR addresses various client bugs (some of which were caught by Sentry in production, some of which I found during the process).

Fixed Bugs

• Sentry caught this error when a request was unsuccessful: "Cannot read properties of undefined (reading 'results')". This can be solved with the "?" optional chaining operator wherever we access .data.results in rest.ts
• The previews in the basemap options menu were broken due to the format of the bounds value. I don't know what changed to break this since I implemented it, but converting the format of the bounds fixed it.
• The screenshot feature was broken, raising the following error: "Unsupported color format color()". I swapped out html2canvas for html2canvas-pro, which is a fork of the original with advanced color support. Again, I don't know what changed since I implemented screenshots, but the dependency swap fixes it.
• In the basemap creation dialog on the "MapLibre Style JSON" tab, the instructions state that you can paste JSON or you can specify a URL. However, the validation was broken if you pasted a URL; it tried to validate that string instead of the content at the url. I added a fetch statement wrapped in a try-except to handle this.

Other Improvements

• I fixed a few styling things that I noticed: some icons lacked colors and the spacing was too compact around the project config section of the left sidebar
• The menu to toggle the visibility of panels was a bit frustrating; you could click the name of a panel and it would animate like the click did something, but the toggle would only apply if you clicked directly on the checkbox. I fixed this so that clicking anywhere on the list item would apply the toggle.