consolidate all external links through external_link component

Add icon={false} option to external_link for links with their own
visual indicator. Migrate remaining manual target="_blank" links:
email settings adapter links, product show provider edit, card radio
links, social link cards/icons, page renderer tracking and video
fallback. Every external link in the codebase now goes through the
single component — one place to change rel, target, or sr-only text.

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

lib/berrypod_web/live/admin/email_settings.ex

@@ -268,16 +268,15 @@ defmodule BerrypodWeb.Admin.EmailSettings do
               <div>
                 <h3 class="admin-section-subheading">
                   {adapter.name}
-                  <a
+                  <.external_link
                     :if={adapter.url}
                     href={adapter.url}
-                    target="_blank"
-                    rel="noopener noreferrer"
+                    icon={false}
                     class="admin-link-subtle admin-adapter-link"
-                    aria-label={adapter.name <> " website (opens in new tab)"}
+                    aria-label={adapter.name <> " website"}
                   >
                     &nearr;
-                  </a>
+                  </.external_link>
                 </h3>
                 <p class="admin-section-desc">{adapter.description}</p>
               </div>

lib/berrypod_web/live/admin/product_show.ex

@@ -98,17 +98,15 @@ defmodule BerrypodWeb.Admin.ProductShow do
         <.status_badge status={@product.status} />
       </div>
       <:actions>
-        <.link
+        <.external_link
           :if={provider_edit_url(@product)}
           href={provider_edit_url(@product)}
-          target="_blank"
-          rel="noopener noreferrer"
+          icon={false}
           class="admin-btn admin-btn-ghost admin-btn-sm"
         >
           Edit on {provider_label(@product)}
           <.icon name="hero-arrow-top-right-on-square-mini" class="size-4" />
-          <span class="sr-only">(opens in new tab)</span>
-        </.link>
+        </.external_link>
         <.link
           navigate={~p"/products/#{@product.slug}"}
           class="admin-btn admin-btn-ghost admin-btn-sm"