WebXR support and more bug fixes!

One of the main things I regretted not finishing before the end of the jam was WebXR support - and now here it is! Even multiplayer works on the web :-)

I've tested with the web browser built into the Meta Quest, but it should work with desktop browsers and PCVR as well, although, I don't know how well hand-tracking will work on PCVR in any case.

And there's also a couple of minor bug fixes:

• Use Meta's hand mesh for the weapon examples when available
• Improved fallback (no delay) when Meta's hand mesh extension isn't available (like on Pico and WebXR)
• Multiplayer: Prevent getting stuck in a loop when the WebSocket fails to connect
• Fix issues with a match continuing to run in the background if you press "Leave Match" at the wrong moment

There are still n issue with gesture detection getting "stuck", which is the most frustrating bug when playing the game. I've opened an issue on the CARL project (which we're using for the gesture detection), and if we manage to fix it, I'll make one more release. Otherwise, this may be the last post-jam update for this little project :-)