added frontend and made it usable

frontend/templates/_pager.html.twig

@@ -0,0 +1,24 @@
+{#
+  Compact pager: first / previous / current / next / last — deliberately
+  not a full list of page numbers, since result sets here can run into
+  the hundreds of pages.
+
+  Params:
+    currentPage, totalPages: integers
+    routeName: the route to link back to
+    routeParams: all params to preserve *except* `page` (e.g. category,
+      q, when, lat, lon, range)
+#}
+{% if totalPages > 1 %}
+  <nav class="pager" aria-label="Pagination">
+    {% if currentPage > 1 %}
+      <a href="{{ path(routeName, routeParams|merge({page: 1})) }}" aria-label="First page">« First</a>
+      <a href="{{ path(routeName, routeParams|merge({page: currentPage - 1})) }}" aria-label="Previous page">‹ Prev</a>
+    {% endif %}
+    <span class="is-active">Page {{ currentPage }} of {{ totalPages }}</span>
+    {% if currentPage < totalPages %}
+      <a href="{{ path(routeName, routeParams|merge({page: currentPage + 1})) }}" aria-label="Next page">Next ›</a>
+      <a href="{{ path(routeName, routeParams|merge({page: totalPages})) }}" aria-label="Last page">Last »</a>
+    {% endif %}
+  </nav>
+{% endif %}