feat: improve email invitation label for clarity and add navigation on guest join

src/i18n/de.json

@@ -518,7 +518,7 @@
     "addressLabel": "Benutzeradresse",
     "addressPlaceholder": "@benutzer@andere-instanz.com",
     "addressHint": "Format: @Benutzername@Domain der Redlight-Instanz",
-    "emailLabel": "Oder per E-Mail einladen",
+    "emailLabel": "Per E-Mail einladen",
     "emailPlaceholder": "name@beispiel.de, name2@beispiel.de",
     "emailHint": "Eine oder mehrere E-Mail-Adressen, durch Komma getrennt",
     "messageLabel": "Nachricht (optional)",

src/i18n/en.json

@@ -518,7 +518,7 @@
     "addressLabel": "User address",
     "addressPlaceholder": "@user@other-instance.com",
     "addressHint": "Format: @username@domain of the Redlight instance",
-    "emailLabel": "Or invite by email",
+    "emailLabel": "Invite by email",
     "emailPlaceholder": "name@example.com, name2@example.com",
     "emailHint": "Enter one or more email addresses, separated by commas",
     "messageLabel": "Message (optional)",