feat: add backups feature

tests/test_settings.py

@@ -190,6 +190,28 @@ class SettingsTests(unittest.TestCase):
 
         self.assertFalse(settings.SUPPORT_ADMIN_EMAIL_NOTIFICATIONS_ENABLED)
 
+    def test_backup_defaults_are_safe_and_blank_targets_use_log_fallback(self):
+        settings = Settings(
+            _env_file=None,
+            BOT_TOKEN="token",
+            POSTGRES_USER="app_user",
+            POSTGRES_PASSWORD="app_password",
+            BACKUP_CHAT_ID="",
+            BACKUP_THREAD_ID="",
+        )
+
+        self.assertFalse(settings.BACKUP_ENABLED)
+        self.assertEqual(settings.BACKUP_INTERVAL_SECONDS, 3600)
+        self.assertEqual(settings.BACKUP_DIR, "data/backups")
+        self.assertEqual(settings.BACKUP_LOCAL_RETENTION, 100)
+        self.assertIsNone(settings.BACKUP_CHAT_ID)
+        self.assertIsNone(settings.BACKUP_THREAD_ID)
+        self.assertEqual(settings.BACKUP_COMPOSE_SOURCE_DIR, "/app/compose-source")
+        self.assertIsNone(settings.BACKUP_COMPOSE_RESTORE_DIR)
+        self.assertEqual(settings.BACKUP_PG_RESTORE_PATH, "pg_restore")
+        self.assertTrue(settings.BACKUP_ARCHIVE_SIGNATURE_REQUIRED)
+        self.assertIsNone(settings.BACKUP_ARCHIVE_SIGNATURE_SECRET)
+
     def test_subscription_purchase_description_is_localized_and_toggleable(self):
         settings = Settings(
             _env_file=None,