add: adicionando base.html e export.html

fix: corrige duplicação da navegação "Ínicio" no breadcrumbs, sobrescrevendo corretamente o bloco nav-breadcrumbs do Admin para evitar repetição. Esse bloco estava contido no import_export/base.html

sigi/templates/admin/import_export/base.html

@@ -0,0 +1,23 @@
+{% extends "admin/base_site.html" %}
+{% load i18n admin_modify %}
+{% load admin_urls %}
+{% load static %}
+
+{% block extrastyle %}{{ block.super }}<link rel="stylesheet" type="text/css" href="{% static "admin/css/forms.css" %}" />{% endblock %}
+
+{% if not is_popup %}
+  {% block nav-breadcrumbs %}
+    <nav aria-label="{% translate 'Breadcrumbs' %}">
+      {% block breadcrumbs %}
+        <div class="breadcrumbs">
+          <a href="{% url 'admin:index' %}">{% translate 'Home' %}</a>
+          &rsaquo; <a href="{% url 'admin:app_list' app_label=opts.app_label %}">{{ opts.app_config.verbose_name }}</a>
+          &rsaquo; <a href="{% url opts|admin_urlname:'changelist' %}">{{ opts.verbose_name_plural|capfirst }}</a>
+          &rsaquo; {% block breadcrumbs_last %}{% endblock %}
+        </div>
+      {% endblock %}
+    </nav>
+  {% endblock %}
+{% endif %}
+
+{% block bodyclass %}{{ block.super }} {{ opts.app_label }}-{{ opts.object_name.lower }} change-form{% endblock %}

sigi/templates/admin/import_export/export.html

@@ -0,0 +1,90 @@
+{% extends "admin/import_export/base.html" %}
+{% load i18n %}
+{% load admin_urls %}
+{% load import_export_tags %}
+
+{% block extrahead %}{{ block.super }}
+<script type="text/javascript" src="{% url 'admin:jsi18n' %}"></script>
+{{ form.media }}
+{% endblock %}
+
+
+{% block breadcrumbs_last %}
+{% translate "Export" %}
+{% endblock %}
+
+
+{% block content %}
+{% if form.errors %}
+  {{ form.errors }}
+{% endif %}
+<form action="{{ export_url }}" method="POST">
+  {% csrf_token %}
+    {# export request has originated from an Admin UI action #}
+    {% if form.initial.export_items %}
+      <p>
+      {% blocktranslate count len=form.initial.export_items|length %}
+        Export {{ len }} selected item.
+        {% plural %}
+        Export {{ len }} selected items.
+      {% endblocktranslate %}
+      </p>
+    {% endif %}
+
+  {# fields list is not required with selectable fields form #}
+  {% if not form.is_selectable_fields_form %}
+    {% include "admin/import_export/resource_fields_list.html" with import_or_export="export" %}
+  {% endif %}
+
+  <fieldset class="module">
+    {% for field in form.visible_fields %}
+      <div
+        {% if field.field.is_selectable_field %}
+          {# all fields are visible by default, JS will hide unselected resource fields on load #}
+
+          class="selectable-field-export-row"
+          {# resource index will be used for showing-hiding fields #}
+          resource-index="{{ field.field.resource_index }}"
+        {% else %}
+          class="form-row aligned"
+        {% endif %}
+      >
+        {% if field.field.initial_field %}
+          <p style="padding: 0;">{% translate "This exporter will export the following fields: " %}</p>
+        {% endif %}
+        {{ field.errors }}
+
+        {% if not field.field.is_selectable_field %}
+          {{ field.label_tag }}
+        {% endif %}
+
+        {% if field.field.widget.attrs.readonly %}
+          {{ field.field.value }}
+          {{ field.as_hidden }}
+          {% else %}
+          {{ field }}
+        {% endif %}
+
+        {% if field.field.is_selectable_field %}
+          {{ field.label_tag }}
+        {% endif %}
+
+        {% if field.field.help_text %}
+        <p class="help">{{ field.field.help_text|safe }}</p>
+        {% endif %}
+      </div>
+    {% endfor %}
+    {% for field in form.hidden_fields %}
+        {{ field }}
+    {% endfor %}
+  </fieldset>
+
+  <div>
+    {{ form.non_field_errors }}
+  </div>
+
+  <div class="submit-row">
+    <input type="submit" class="default" value="{% translate "Submit" %}">
+  </div>
+</form>
+{% endblock %}