fix: add missing katex dependency (#1301)

Co-authored-by: Claude <noreply@anthropic.com>

Author: tonypan2

package.json

@@ -52,6 +52,7 @@
     "fast-deep-equal": "^3.1.3",
     "framer-motion": "^11.3.19",
     "geist": "^1.3.1",
+    "katex": "^0.16.25",
     "lucide-react": "^0.446.0",
     "nanoid": "^5.0.8",
     "next": "15.3.0-canary.31",