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

RIGS/templates/event_detail.html

@@ -7,10 +7,10 @@
     {{ block.super }}
 
     <script>
-    $(document).keydown(function(e) {
+    document.addEventListener('keydown', function(e) {
         if ((e.ctrlKey || e.metaKey) && e.keyCode == 80) {
             window.open("{% url 'event_print' object.pk %}", '_blank');
-            return false;
+            e.preventDefault();
         }
     });
     </script>
@@ -20,7 +20,7 @@
 <div class="row my-3 py-3">
     {% if not is_ajax %}
         {% if perms.RIGS.view_event %}
-        <div class="col-sm-12 text-right">
+        <div class="col-sm-12 text-end">
             {% include 'partials/event_detail_buttons.html' %}
         </div>
         {% endif %}
@@ -50,7 +50,7 @@
     {% endif %}
     {% endif %}
     {% if not is_ajax and perms.RIGS.view_event %}
-    <div class="col-sm-12 text-right">
+    <div class="col-sm-12 text-end">
         {% include 'partials/event_detail_buttons.html' %}
     </div>
     {% endif %}
@@ -73,13 +73,13 @@
         {% include 'partials/crew_list.html' %}
 
         {% if not is_ajax and perms.RIGS.view_event %}
-        <div class="col-sm-12 text-right">
+        <div class="col-sm-12 text-end">
             {% include 'partials/event_detail_buttons.html' %}
         </div>
         {% endif %}
     {% endif %}
     {% if not is_ajax and perms.RIGS.view_event %}
-        <div class="col-sm-12 text-right">
+        <div class="col-sm-12 text-end">
             {% include 'partials/last_edited.html' with target="event_history" %}
         </div>
     {% endif %}