temp: Add dummy model for testing migrations

This will be followed later by a revert of the model and addition of a
corresponding second migration.

Output of `sqlmigrate edx_arch_experiments 0001_initial`:

```
CREATE TABLE "edx_arch_experiments_boms227" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, "dummy_field" varchar(50) NOT NULL);
```

With `--backwards`:

```
DROP TABLE "edx_arch_experiments_boms227";
```

BOMS-227

Author: timmc-edx

CHANGELOG.rst

@@ -14,6 +14,12 @@ Change Log
 Unreleased
 **********
 
+[7.1.0] - 2025-11-17
+********************
+Added
+=====
+* Dummy model for testing migrations and rollback.
+
 [7.0.0] - 2025-01-30
 ********************
 

edx_arch_experiments/__init__.py

@@ -2,4 +2,4 @@
 A plugin to include applications under development by the architecture team at 2U.
 """
 
-__version__ = '7.0.0'
+__version__ = '7.1.0'

edx_arch_experiments/migrations/0001_initial.py

@@ -0,0 +1,21 @@
+# Generated by Django 4.2.25 on 2025-11-13 17:21
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Boms227',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('dummy_field', models.CharField(max_length=50)),
+            ],
+        ),
+    ]

edx_arch_experiments/migrations/__init__.py

@@ -0,0 +1,18 @@
+"""
+Models for testing migrations.
+
+We don't actually store any data in this Django app. The models here are purely
+for pipeline and deployment testing purposes.
+"""
+
+from django.db import models
+
+
+class Boms227(models.Model):
+    """
+    Model for testing migrations and rollbacks. See BOMS-227.
+
+    .. no_pii: No data should actually be stored in this table.
+    """
+
+    dummy_field = models.CharField(max_length=50)