fix: update react-dom to 19.2.3 to match react version

React requires both react and react-dom packages to have the exact same
version. This commit updates react-dom from 19.2.1 to 19.2.3 to match
the react version updated by Dependabot in PR #240.

Fixes failing unit tests that reported:
"Incompatible React versions: The 'react' and 'react-dom' packages must
have the exact same version."

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Author: mchestr

package-lock.json

@@ -43,7 +43,7 @@
     "react": "^19.2.3",
     "react-chartjs-2": "^5.3.1",
     "react-countup": "^6.5.3",
-    "react-dom": "^19.2.1",
+    "react-dom": "^19.2.3",
     "react-markdown": "^10.1.0",
     "tailwind-merge": "^3.4.0",
     "winston": "^3.19.0",