✨(frontend) login and logout from Posthog

Following Posthog documentation, login and logout users directly
from the client. Note: Logout function should be encapsulate in
a proper function.

src/frontend/src/features/auth/api/useUser.tsx

@@ -2,6 +2,8 @@ import { useQuery } from '@tanstack/react-query'
 import { keys } from '@/api/queryKeys'
 import { fetchUser } from './fetchUser'
 import { type ApiUser } from './ApiUser'
+import { useEffect } from 'react'
+import posthog from 'posthog-js'
 
 /**
  * returns info about currently logged in user
@@ -15,6 +17,12 @@ export const useUser = () => {
     staleTime: 1000 * 60 * 60, // 1 hour
   })
 
+  useEffect(() => {
+    if (query.data && query.data.id && !posthog._isIdentified()) {
+      posthog.identify('query.data.id', { email: query.data.email })
+    }
+  }, [query.data])
+
   const isLoggedIn =
     query.status === 'success' ? query.data !== false : undefined
   const isLoggedOut = isLoggedIn === false

src/frontend/src/layout/Header.tsx

@@ -9,6 +9,7 @@ import { useMatchesRoute } from '@/navigation/useMatchesRoute'
 import { Feedback } from '@/components/Feedback'
 import { Menu } from '@/primitives/Menu'
 import { MenuList } from '@/primitives/MenuList'
+import posthog from 'posthog-js'
 
 export const Header = () => {
   const { t } = useTranslation()
@@ -79,6 +80,7 @@ export const Header = () => {
                   items={[{ value: 'logout', label: t('logout') }]}
                   onAction={(value) => {
                     if (value === 'logout') {
+                      posthog.reset()
                       window.location.href = logoutUrl()
                     }
                   }}