`std.debug.assert(x)` _is not_ the same as `if (!x) unreachable`
because the function call is not `inline`. Since it's not inline the
Zig compiler will try to compile any code that might otherwise be
unreachable.
Also, added a CI test that compiles Ghostty in a Debian 12 container to
ensure that regressions do not happen.
0ce1342263