Add cart-mini + auth-menu fragments to all apps, fix like button

- Market, events, federation, account now fetch cart-mini, auth-menu,
  and nav-tree fragments concurrently (matching blog's pattern)
- Move like button template to shared/browser/templates/ so blog can
  find it without needing market's templates in its container

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

shared/browser/templates/_types/browse/like/button.html

@@ -0,0 +1,20 @@
+<button
+  class="flex items-center gap-1 {% if liked %} text-red-600 {% else %} text-stone-300 {% endif %} hover:text-red-600 transition-colors w-[1em] h-[1em]"
+  hx-post="{{ like_url if like_url else url_for('market.browse.product.like_toggle', product_slug=slug)|host }}"
+  hx-target="this"
+  hx-swap="outerHTML"
+  hx-push-url="false"
+  hx-headers='{"X-CSRFToken": "{{ csrf_token() }}"}'
+  hx-swap-settle="0ms"
+  {% if liked %}
+    aria-label="Unlike this {{ item_type if item_type else 'product' }}"
+  {% else %}
+    aria-label="Like this {{ item_type if item_type else 'product' }}"
+  {% endif %}
+>
+  {% if liked %}
+    <i aria-hidden="true" class="fa-solid fa-heart"></i>
+  {% else %}
+    <i aria-hidden="true" class="fa-regular fa-heart"></i>
+  {% endif %}
+</button>