Fix cart sign-in button: use plain link instead of HTMX

The login URL is cross-origin (blog app), so hx-get can't load it
into the current page. Use a regular <a href> for cross-app navigation.

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

browser/templates/_types/cart/_cart.html

@@ -117,23 +117,13 @@
           </form>
         {% else %}
           {% set href=login_url(request.url) %}
-          <div
-            class="w-full flex"
-          >
+          <div class="w-full flex">
             <a
               href="{{ href }}"
-              hx-get="{{ href }}"
-              hx-target="#main-panel"
-              hx-select ="{{hx_select_search}}"
-              hx-swap="outerHTML"
-              hx-push-url="true"
-              aria-selected="{{ 'true' if local_href == request.path else 'false' }}"
-              class="w-full cursor-pointer flex flex-row items-center justify-center p-3 gap-2 rounded bg-stone-200 text-black {{select_colours}}"
-              data-close-details
+              class="w-full cursor-pointer flex flex-row items-center justify-center p-3 gap-2 rounded bg-stone-200 text-black hover:bg-stone-300 transition"
             >
               <i class="fa-solid fa-key"></i>
               <span>sign in or register to checkout</span>
-
             </a>
           </div>