Add indexes on fields on which we order and vice versa

Triggered by issue_event_list being more than 5s on "emu" (my 1,500,000 event
test-machine). Reason: sorting those events on non-indexed field. Switching
to a field-with-index solved it.

I then analysed (grepped) for "ordering" and "order_by" and set indexes
accordingly and more or less indiscriminately (i.e. even on tables that are
assumed to have relatively few rows, such as Project & Team).

snappea/migrations/0004_task_snappea_tas_created_eb0824_idx.py

@@ -0,0 +1,19 @@
+# Generated by Django 4.2.18 on 2025-02-04 20:14
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("snappea", "0003_task_created_at"),
+    ]
+
+    operations = [
+        migrations.AddIndex(
+            model_name="task",
+            index=models.Index(
+                fields=["created_at"], name="snappea_tas_created_eb0824_idx"
+            ),
+        ),
+    ]

snappea/models.py

@@ -15,6 +15,11 @@ class Task(models.Model):
     def __str__(self):
         return self.task_name
 
+    class Meta:
+        indexes = [
+            models.Index(fields=['created_at']),
+        ]
+
 
 def wakeup_server():
     wakeup_file = os.path.join(get_settings().WAKEUP_CALLS_DIR, thread_uuid)