Bootstrap 5 & remove jQuery (#661)

* build: move frontend assets to Bootstrap 5.3 and Tom Select

* feat: migrate templates and scripts to Bootstrap 5, dropping jQuery

Templates
- Rename Bootstrap 4 classes and data attributes (data-bs-*, ms-/me-/ps-/pe-,
  text-start/end, form-group -> mb-3, input-group wrappers removed, badges,
  custom controls -> form-check/form-select, media -> d-flex, btn-close, ...)
- Dark mode now uses Bootstrap 5.3 colour modes (data-bs-theme on <html>),
  set from <head> to avoid a flash of the light theme
- Remove the Bootstrap 4 /bootstrap/ demo page
- Contextual table classes (table-success etc.) still work as plain
  backgrounds for the rigboard key

JavaScript
- Remove jQuery: src.js/interaction.js and every inline template script are
  rewritten in plain JS on top of small helpers (helpers.js, bundled with
  Bootstrap into jpop.js so inline scripts can use them)
- Replace bootstrap-select/ajax-bootstrap-select with Tom Select. The remote
  search now sends the `q` parameter and reads `text`, which is what the
  API actually uses (the old picker sent `term` and read `label`)
- HTML fragments are fetched with an X-Requested-With header so views keep
  rendering their modal variants, and fetched scripts are re-executed
- Remove the Bootstrap 4 plugin script includes

* fix: stop rigboard header buttons stretching to full width under Bootstrap 5

* fix: restore dark-mode brand colours and contextual table colours under Bootstrap 5

* fix: brighten dark-mode links and make coloured card outlines visible

* fix: calendar layout and grid borders, navbar search button width, guard missing modal links

* fix: readable text in dark-mode Tom Select inputs and placeholders, restore form-control column widths

* build: split the Dockerfile into cached stages with prod and dev targets

* deploy: make compose.yml development-only with live reload, and document it

* fix: keep badge text colour for links inside badges

* fix: restore table-bordered grid lines in dark mode

* fix: include Bootstrap's progress styles and keep progress labels readable

versioning/templates/activity_feed_data.html

@@ -9,7 +9,7 @@
 {% block content %}
 {% cache None feed_data request.user %}
 <div class="list-group-item">
-    <div class="media">
+    <div class="d-flex">
     {% for version in object_list %}
             {% if not version.withPrevious %}
                 {% if not forloop.first %}
@@ -17,9 +17,9 @@
                 </div> {#/.media#}
                 </div>
                 <div class="list-group-item">
-                <div class="media">
+                <div class="d-flex">
                 {% endif %}
-                    <div class="align-self-start mr-3">
+                    <div class="align-self-start me-3">
                     {% if version.revision.user %}
                         <a href="{% url 'profile_detail' pk=version.revision.user.pk %}" class="modal-href">
                         <img class="media-object rounded" src="{{ version.revision.user.profile_picture}}" />
@@ -27,11 +27,11 @@
                         <img class="media-object rounded" src="{% static 'imgs/pyrigs-avatar.png' %}" />
                     {% endif %}
                     </div>
-                    <div class="media-body">
+                    <div class="flex-grow-1">
                     <h5>
                         {{ version.revision.user.name|default:'System' }}
                         {% if version.revision.user %}</a>{% endif %}
-                        <span class="float-right"><small><span class="fas fa-clock"></span> <span class="time">{{version.revision.date_created|date:"c"}}</span> ({{version.revision.date_created}})</small></span>
+                        <span class="float-end"><small><span class="fas fa-clock"></span> <span class="time">{{version.revision.date_created|date:"c"}}</span> ({{version.revision.date_created}})</small></span>
                     </h5>
             {% endif %}
                     <p>
@@ -51,7 +51,7 @@
 
 {% block js %}
 <script>
-$(document).ready(function() {
+ready(function() {
     const times = document.getElementsByClassName("time");
     var i;
     for(i = 0; i < times.length; i++) {