Update to Zig 0.16.0 (#962)

Signed-off-by: AnErrupTion <anerruption@disroot.org>

## What are the changes about?

Ports the code base to Zig 0.16.0.

## What existing issue does this resolve?

N/A

## Pre-requisites

- [x] I have tested & confirmed the changes work locally
- [x] I have run `zig fmt` throughout my changes

Reviewed-on: https://codeberg.org/fairyglade/ly/pulls/962

create_vendor_tarball.sh

@@ -0,0 +1,2 @@
+#!/bin/sh
+tar --zstd -cvf vendor.tar.zst zig-pkg ly-ui/zig-pkg ly-core/zig-pkg