build(deps): bump katex from 0.16.47 to 0.18.2 in /ui

Bumps [katex](https://github.com/KaTeX/KaTeX) from 0.16.47 to 0.18.2.
- [Release notes](https://github.com/KaTeX/KaTeX/releases)
- [Changelog](https://github.com/KaTeX/KaTeX/blob/main/CHANGELOG.md)
- [Commits](https://github.com/KaTeX/KaTeX/compare/v0.16.47...v0.18.2)

---
updated-dependencies:
- dependency-name: katex
  dependency-version: 0.18.2
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

ui/desktop/package.json

@@ -83,7 +83,7 @@
     "electron-window-state": "^5.0.3",
     "express": "^5.2.1",
     "framer-motion": "^13.2.0",
-    "katex": "0.16.47",
+    "katex": "0.18.2",
     "lodash": "^4.18.1",
     "lucide-react": "^0.575.0",
     "react": "^19.2.8",