add providers, LiveDashboard, errors links to admin sidebar

Providers was a hidden page with no nav link. Also adds
LiveDashboard and ErrorTracker to the sidebar footer, and
styles the provider dropdown menu items.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/berrypod_web/components/layouts/admin.html.heex

@@ -75,6 +75,14 @@
               <.icon name="hero-cube" class="size-5" /> Products
             </.link>
           </li>
+          <li>
+            <.link
+              navigate={~p"/admin/providers"}
+              class={admin_nav_active?(@current_path, "/admin/providers")}
+            >
+              <.icon name="hero-link" class="size-5" /> Providers
+            </.link>
+          </li>
           <li>
             <.link
               href={~p"/admin/theme"}
@@ -102,6 +110,16 @@
               <.icon name="hero-arrow-top-right-on-square" class="size-5" /> View shop
             </.link>
           </li>
+          <li>
+            <.link href={~p"/admin/dashboard"}>
+              <.icon name="hero-chart-bar" class="size-5" /> LiveDashboard
+            </.link>
+          </li>
+          <li>
+            <.link href={~p"/admin/errors"}>
+              <.icon name="hero-bug-ant" class="size-5" /> Errors
+            </.link>
+          </li>
           <li>
             <.link href={~p"/users/log-out"} method="delete">
               <.icon name="hero-arrow-right-start-on-rectangle" class="size-5" /> Log out