Fix KaTeX math rendering: use correct arithmatex delimiters

arithmatex generic mode outputs \(...\) and \[...\], not $...$ and $$...$$

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: 0xC000005

docs/javascripts/katex.js

@@ -1,8 +1,8 @@
 document$.subscribe(({ body }) => {
   renderMathInElement(body, {
     delimiters: [
-      { left: "$$", right: "$$", display: true },
-      { left: "$", right: "$", display: false },
+      { left: "\\(", right: "\\)", display: false },
+      { left: "\\[", right: "\\]", display: true },
     ],
   });
 });