feat: replace email flows with in-app notifications

Add recipient notification detail and filtering, a queued admin composer, and contextual automatic titles. Retire email delivery, obsolete auth routes, newsletter data, and related templates and settings.

apps/communications/migrations/0003_remove_announcement_email_sent_and_more.py

@@ -0,0 +1,46 @@
+# Generated by Django 5.2.5 on 2026-09-26 07:57
+
+from django.db import migrations, models
+
+
+def delete_newsletter_announcements(apps, schema_editor):
+    apps.get_model('communications', 'Announcement')._base_manager.filter(announcement_type='newsletter').delete()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('communications', '0002_initial'),
+    ]
+
+    operations = [
+        migrations.RunPython(delete_newsletter_announcements, migrations.RunPython.noop),
+        migrations.RemoveField(
+            model_name='announcement',
+            name='email_sent',
+        ),
+        migrations.RemoveField(
+            model_name='announcement',
+            name='push_sent',
+        ),
+        migrations.RemoveField(
+            model_name='announcement',
+            name='send_email',
+        ),
+        migrations.RemoveField(
+            model_name='announcement',
+            name='send_push',
+        ),
+        migrations.RemoveField(
+            model_name='announcement',
+            name='target_audience',
+        ),
+        migrations.AlterField(
+            model_name='announcement',
+            name='announcement_type',
+            field=models.CharField(choices=[('general', 'General'), ('event', 'Event'), ('academic', 'Academic'), ('urgent', 'Urgent')], default='general', max_length=20, verbose_name='Type'),
+        ),
+        migrations.DeleteModel(
+            name='NewsletterSubscription',
+        ),
+    ]