Give every model created/modified timestamps

TimeStampedModel goes on UUIDModel, so all 28 domain models get row birthdays in
one place. Without them the dashboard can only ever describe the present: "42
members" is knowable, "members joined this month" is not, and no metric can show
direction.

Order dropped its own created/modified -- redeclaring a field from an abstract
base is an error, and its column survives as a plain AlterField (verbose_name
only), so no order data moves.

Note for reading early charts: auto_now_add backfills existing rows with a single
migration timestamp, so everything that predates this commit shares one birthday
and will show up as a spike at that instant rather than as real history.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

teams/migrations/0004_position_created_position_modified_and_more.py

@@ -0,0 +1,58 @@
+# Generated by Django 6.0.6 on 2026-07-13 22:51
+
+import datetime
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('teams', '0003_position_management_position_implies_staff_position'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='position',
+            name='created',
+            field=models.DateTimeField(auto_now_add=True, default=datetime.datetime(2026, 7, 13, 22, 51, 35, 566331, tzinfo=datetime.timezone.utc), verbose_name='created'),
+            preserve_default=False,
+        ),
+        migrations.AddField(
+            model_name='position',
+            name='modified',
+            field=models.DateTimeField(auto_now=True, verbose_name='modified'),
+        ),
+        migrations.AddField(
+            model_name='staffassignment',
+            name='created',
+            field=models.DateTimeField(auto_now_add=True, default=datetime.datetime(2026, 7, 13, 22, 51, 35, 566347, tzinfo=datetime.timezone.utc), verbose_name='created'),
+            preserve_default=False,
+        ),
+        migrations.AddField(
+            model_name='staffassignment',
+            name='modified',
+            field=models.DateTimeField(auto_now=True, verbose_name='modified'),
+        ),
+        migrations.AddField(
+            model_name='team',
+            name='created',
+            field=models.DateTimeField(auto_now_add=True, default=datetime.datetime(2026, 7, 13, 22, 51, 35, 566410, tzinfo=datetime.timezone.utc), verbose_name='created'),
+            preserve_default=False,
+        ),
+        migrations.AddField(
+            model_name='team',
+            name='modified',
+            field=models.DateTimeField(auto_now=True, verbose_name='modified'),
+        ),
+        migrations.AddField(
+            model_name='teammembership',
+            name='created',
+            field=models.DateTimeField(auto_now_add=True, default=datetime.datetime(2026, 7, 13, 22, 51, 35, 566427, tzinfo=datetime.timezone.utc), verbose_name='created'),
+            preserve_default=False,
+        ),
+        migrations.AddField(
+            model_name='teammembership',
+            name='modified',
+            field=models.DateTimeField(auto_now=True, verbose_name='modified'),
+        ),
+    ]