🚸(frontend) follow antoine's remarks on homepage and header

- show the header on homepage. Not sure we want any header on this app
actually but I guess he's right since we have one it feels more
consistent to have it everywhere
- show logged in email in header. ditched it because i didn't quite get
the value of showing it all the time in this app but i guess it's better
than nothing
- remove user info from settings. Since they are back in the header, no
need

src/frontend/src/locales/de/settings.json

@@ -1,9 +1,4 @@
 {
-  "account": {
-    "currentlyLoggedAs": "",
-    "heading": "",
-    "youAreNotLoggedIn": ""
-  },
   "dialog": {
     "heading": ""
   },