fix: hydratation error with age calculation

hooks/useIsMounted.ts

@@ -0,0 +1,15 @@
+import { useEffect, useState } from "react"
+
+export interface UseIsMountedResult {
+  isMounted: boolean
+}
+
+export const useIsMounted = (): UseIsMountedResult => {
+  const [isMounted, setIsMounted] = useState(false)
+
+  useEffect(() => {
+    setIsMounted(true)
+  }, [])
+
+  return { isMounted }
+}