Handle equation numbers/tags in KaTeX

[gnprice]

As in \tag{1}, which causes a right-aligned "(1)" to appear at the end of a math block.

Requested by a user here: #mobile > LaTeX long equations not rendering @ 💬
who adds (#mobile > LaTeX long equations not rendering @ 💬):

The use case of \tag can be common in a research chat where the group often discusses a specific equation from math-heavy literatures.

[gnprice]

The CSS for this (here) is, excerpting:

.katex-display {
    > .katex {
        > .katex-html {
            > .tag {
                position: absolute;
                right: 0;
            }
        }
    }
}

So probably not complex to implement.