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/base_rigs.html

@@ -14,7 +14,7 @@
 {% if user.is_authenticated %}
     <li class="nav-item"><a class="nav-link" href="/">Home</a></li>
     <li class="nav-item dropdown">
-      <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownRigboard" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
+      <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownRigboard" role="button" data-bs-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
         Rigboard
       </a>
       <div class="dropdown-menu" aria-labelledby="navbarDropdownRigboard">
@@ -42,15 +42,15 @@
       {% total_invoices_todo as todo %}
       {% invoices_waiting as waiting %}
       {% invoices_outstanding as outstanding %}
-      <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownInvoices" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
-        Invoices <span class="badge {% if todo == 0 %}badge-success{% else %}badge-danger{% endif %} badge-pill">{{ todo }}</span>
+      <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownInvoices" role="button" data-bs-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
+        Invoices <span class="badge {% if todo == 0 %}text-bg-success{% else %}text-bg-danger{% endif %} rounded-pill">{{ todo }}</span>
       </a>
       <div class="dropdown-menu" aria-labelledby="navbarDropdownInvoices">
         <a class="dropdown-item" href="{% url 'invoice_dashboard' %}"><span class="fas fa-chart-line"></span> Dashboard</a>
         {% if perms.RIGS.add_invoice %}
-        <a class="dropdown-item text-nowrap" href="{% url 'invoice_waiting' %}"><span class="fas fa-briefcase text-danger"></span> Waiting <span class="badge {% if waiting == 0 %}badge-success{% else %}badge-danger{% endif %} badge-pill">{{ waiting }}</span></a>
+        <a class="dropdown-item text-nowrap" href="{% url 'invoice_waiting' %}"><span class="fas fa-briefcase text-danger"></span> Waiting <span class="badge {% if waiting == 0 %}text-bg-success{% else %}text-bg-danger{% endif %} rounded-pill">{{ waiting }}</span></a>
         {% endif %}
-        <a class="dropdown-item" href="{% url 'invoice_list' %}"><span class="fas fa-pound-sign text-warning"></span> Outstanding <span class="badge {% if outstanding == 0 %}badge-success{% else %}badge-danger{% endif %} badge-pill">{{ outstanding }}</span></a>
+        <a class="dropdown-item" href="{% url 'invoice_list' %}"><span class="fas fa-pound-sign text-warning"></span> Outstanding <span class="badge {% if outstanding == 0 %}text-bg-success{% else %}text-bg-danger{% endif %} rounded-pill">{{ outstanding }}</span></a>
         <a class="dropdown-item" href="{% url 'invoice_archive' %}"><span class="fas fa-book"></span> Archive</a>
       </div>
     </li>
@@ -74,11 +74,4 @@
 
 {% block js %}
 {{ block.super }}
-<script src="{% static 'js/tooltip.js' %}"></script>
-<script src="{% static 'js/popover.js' %}"></script>
-<script>
-    $(function () {
-          $('[data-toggle="tooltip"]').tooltip();
-    })
-</script>
 {% endblock %}