feat: add theme selector to unauthenticated pages

lib/mv_web/live/join_live.ex

@@ -100,13 +100,13 @@ defmodule MvWeb.JoinLive do
                     />
                   </div>
 
-                  <p class="text-sm text-base-content/70">
+                  <p class="text-sm text-base-content/85">
                     {gettext(
                       "By submitting your application you will receive an email with a confirmation link. Once you have confirmed your email address, your application will be reviewed."
                     )}
                   </p>
 
-                  <p class="text-xs text-base-content/60">
+                  <p class="text-xs text-base-content/80">
                     {gettext(
                       "Your details are only used to process your membership application and to contact you. To prevent abuse we also process technical data (e.g. IP address) only as necessary."
                     )}