Add canonical field and update synonym handling in Condition model

- Introduced a new `canonical` ForeignKey field in the Condition model to manage alias relationships.
- Enhanced synonym retrieval methods to prefer canonical names and handle aliases more effectively.
- Updated condition detail templates to reflect canonical status and improved synonym display.
- Implemented migration scripts to establish canonical relationships based on existing synonym links.

atlas/templates/atlas/condition_detail.html

@@ -18,7 +18,7 @@
                 <h5 class="mb-2">Details</h5>
                 <dl class="row">
                         <dt class="col-sm-4">Primary name</dt>
-                        <dd class="col-sm-8">{{ condition.primary }}</dd>
+                        <dd class="col-sm-8">{% if condition.canonical %}No (alias of <a href="{{ condition.canonical.get_absolute_url }}">{{ condition.canonical.name }}</a>){% else %}Yes{% endif %}</dd>
 
                         <dt class="col-sm-4">Subspecialty</dt>
                         <dd class="col-sm-8">

atlas/templates/atlas/finding_detail.html

@@ -12,8 +12,8 @@
     </div>
     <div>
         <h3>Name: {{finding.name}}</h3>
-        Primary name: {{finding.primary}}<br />
-        Synonyms: {{finding.synonym.all|join:", "}}<br />
+    Primary name: {% if finding.canonical %}No (alias of <a href="{{ finding.canonical.get_absolute_url }}">{{ finding.canonical.name }}</a>){% else %}Yes{% endif %}<br />
+    Synonyms: {{ finding.get_synonym_link|safe }}<br />
     </div>
     {% if finding.seriesfinding_set.all %}
         <h4>Associated Cases</h4>

atlas/templates/atlas/partials/_synonyms_list.html

@@ -1,13 +1,15 @@
 {% comment %}Partial that renders the synonyms list + add form. Used by condition_detail and HTMX responses.{% endcomment %}
 {% load static %}
 
-{% if condition.synonym.all %}
-    {% for syn in condition.synonym.all %}
-        <a class="badge bg-secondary text-decoration-none text-white me-1" href="{{ syn.get_absolute_url }}">{{ syn }}</a>
-    {% endfor %}
-{% else %}
-    &mdash;
-{% endif %}
+{% with syns=condition.get_synonyms %}
+    {% if syns %}
+        {% for syn in syns %}
+            <a class="badge bg-secondary text-decoration-none text-white me-1" href="{{ syn.get_absolute_url }}">{{ syn }}</a>
+        {% endfor %}
+    {% else %}
+        &mdash;
+    {% endif %}
+{% endwith %}
 
 {% if request.user.is_authenticated and can_merge %}
     <div class="mt-2 d-flex gap-2">

atlas/templates/atlas/structure_detail.html

@@ -14,8 +14,8 @@
     </div>
     <div>
         <h3>Name: {{structure.name}}</h3>
-        Primary name: {{structure.primary}}<br />
-        Synonyms: {{structure.synonym.all|join:", "}}<br />
+    Primary name: {% if structure.canonical %}No (alias of <a href="{{ structure.canonical.get_absolute_url }}">{{ structure.canonical.name }}</a>){% else %}Yes{% endif %}<br />
+    Synonyms: {{ structure.get_synonym_link|safe }}<br />
     </div>
     <h4>Associated Cases</h4>
     <ul>