feat: admin list filtering and search

templates/_partials/_query_passthrough.html.twig

@@ -0,0 +1,17 @@
+{#
+    Renders query parameters as hidden inputs so they survive a filter submit.
+
+    A filter form only submits its own fields, so anything else that describes the current list —
+    the sorting, the page size, the return URL — has to be carried along explicitly or it is lost
+    the moment somebody searches.
+#}
+{% macro render(values, prefix) %}
+    {%- for key, value in values -%}
+        {%- set name = prefix ? prefix ~ '[' ~ key ~ ']' : key -%}
+        {%- if value is iterable -%}
+            {{ _self.render(value, name) }}
+        {%- else -%}
+            <input type="hidden" name="{{ name }}" value="{{ value }}">
+        {%- endif -%}
+    {%- endfor -%}
+{% endmacro %}