Mint campaign UTM links through the piha.li shortener.

Closes #9.

Auto-insert tracked homepage links in campaign compose, register them with
url_shortening_service, and put short piha.li URLs in SMS, email hrefs, and
postcard QR codes when SHORTENER_* is configured.

site/messaging/templates/messaging/campaign_detail.html

@@ -1,4 +1,5 @@
 {% extends "portal_base.html" %}
+{% load static %}
 {% block title %}{{ campaign.name }} · Campaign{% endblock %}
 {% block topbar_title %}{{ campaign.name }}{% endblock %}
 {% block portal_content %}
@@ -51,6 +52,13 @@
 </div>
 {% endif %}
 
+<div class="panel" style="margin-bottom:16px">
+  <div class="panel-h"><h2>Tracked site link</h2></div>
+  <div class="panel-b">
+    {% include "messaging/_utm_link_panel.html" with utm_live=False utm_medium=campaign.channel utm_campaign_name=campaign.name %}
+  </div>
+</div>
+
 <div class="stat-row" id="campaign-stats">
   <div class="stat-card">
     <div class="label">Messages</div>
@@ -208,7 +216,10 @@
 </div>
 {% endblock %}
 {% block extra_js %}
+<script src="https://cdn.jsdelivr.net/npm/qrcode@1.5.4/build/qrcode.min.js"></script>
+<script src="{% static 'js/campaign-utm.js' %}"></script>
 <script>
+window.MonicaUtm.bindPanel(document.getElementById("utm-link-panel"));
 (function () {
   var panel = document.getElementById("recipients-panel");
   var page = (panel && panel.getAttribute("data-page")) || "1";