feat(auth): add email verification flow

templates/email_form.html

@@ -2,13 +2,13 @@
 {% block title %}Email address | Eternity Project{% endblock %}
 {% block content %}
 <section class="auth-layout">
-  <div class="auth-copy"><span class="signal-label">ACCOUNT DETAILS</span><h1>Update your<br>address.</h1><p>Use an email address you control. Confirm your current password before saving the change.</p></div>
+  <div class="auth-copy"><span class="signal-label">ACCOUNT DETAILS</span><h1>Update your<br>address.</h1><p>Use an email address you control. Confirm your password, then verify the link sent to the new address.</p></div>
   <form class="auth-form" method="post">
     <input type="hidden" name="csrf_token" value="{{ csrf_token() }}">
     <label>Current email<input type="email" value="{{ email or '' }}" readonly></label>
     <label>New email<input name="email" type="email" autocomplete="email" required placeholder="you@example.com"></label>
     <label>Current password<input name="current_password" type="password" autocomplete="current-password" required></label>
-    <button class="button" type="submit">Save email <span aria-hidden="true">→</span></button>
+    <button class="button" type="submit">Send verification <span aria-hidden="true">→</span></button>
   </form>
 </section>
 {% endblock %}