feat(ui): display user email on home page

Updated the home page greeting to show the user's email instead of their first name. This change improves user identification and ensures consistency when the first name is not provided.

freedoi/resolver/templates/resolver/home.html

@@ -64,7 +64,7 @@
   <h2>Get Started</h2>
   {% if user.is_authenticated %}
   <p>
-    Welcome back, {{ user.first_name }}! Use the navigation links above to
+    Welcome back, {{ user.email }}! Use the navigation links above to
     manage your suffixes, and identifiers.
   </p>
   <a class="btn btn-primary" href="{% url 'suffix_list' %}">Manage Suffixes</a>