Faster updates and design tweaks

A bunch of stuff in separate commits:

1. Restore VS Code config files; simplify code a bit in Chart; rename env var VITE_OPEN_BROWSER to just OPEN_BROWSER.
2. Shorten debounce timeout to 50ms for faster updates.
3. Avoid double renders of ChartDataLoader when receiving live states (this helps with #13 (closed) but still not perfect).
4. Tweak design/markup of CurrentDate: italic + bring closer to page title.

5. Tweak design of Messages:
   • use a similar style to some of the cards on the ESRF homepage;
   • increase height of revealed container;
   • add subtle gradient to make it clear that the revealed container is scrollable;
   • replace the details arrow marker with a custom icon;
   • underline on hover;
   • remove overflow:hidden to avoid hiding the focus outline (when tabbing).

closed	open

6. Remove horizontal crosshair from tooltip, and let tooltip follow the cursor. I find it a bit jarring to have the tooltip and horizontal crosshair jump around to follow the plot. What do you think?