Redesign conference form with improved UI organization

• Group form into logical sections with background color and headers
• Add labels and placeholder text

app/views/admin/dashboard/index.html.erb

@@ -109,9 +109,8 @@
               <% if @admin_users.any? %>
                 <div class="flex flex-wrap gap-2">
                   <% @admin_users.each do |user| %>
-                    <%= link_to admin_user_path(user), class: "inline-flex items-center px-3 py-1 rounded-full text-sm bg-purple-100 text-purple-800 dark:bg-purple-900 dark:text-purple-200" do %>
-                      <div class="w-5 h-5 rounded-full mr-2" style="background-color: <%= user.avatar_color %>"></div>
-                      <%= user.name %>
+                    <%= link_to admin_user_path(user) do %>
+                      <%= render "application/user_avatar", user: user %>
                     <% end %>
                   <% end %>
                 </div>
@@ -127,9 +126,8 @@
               <% if @events_admins.any? %>
                 <div class="flex flex-wrap gap-2">
                   <% @events_admins.each do |user| %>
-                    <%= link_to admin_user_path(user), class: "inline-flex items-center px-3 py-1 rounded-full text-sm bg-blue-100 text-blue-800 dark:bg-blue-900 dark:text-blue-200" do %>
-                      <div class="w-5 h-5 rounded-full mr-2" style="background-color: <%= user.avatar_color %>"></div>
-                      <%= user.name %>
+                    <%= link_to admin_user_path(user) do %>
+                      <%= render "application/user_avatar", user: user %>
                     <% end %>
                   <% end %>
                 </div>
@@ -145,9 +143,8 @@
               <% if @shift_coordinators.any? %>
                 <div class="flex flex-wrap gap-2">
                   <% @shift_coordinators.each do |user| %>
-                    <%= link_to admin_user_path(user), class: "inline-flex items-center px-3 py-1 rounded-full text-sm bg-green-100 text-green-800 dark:bg-green-900 dark:text-green-200" do %>
-                      <div class="w-5 h-5 rounded-full mr-2" style="background-color: <%= user.avatar_color %>"></div>
-                      <%= user.name %>
+                    <%= link_to admin_user_path(user) do %>
+                      <%= render "application/user_avatar", user: user %>
                     <% end %>
                   <% end %>
                 </div>