fix: address code review - Alpine.js $set, SQLAlchemy bool filter style

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Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

backend/app/tests/test_mail_sources.py

@@ -147,9 +147,7 @@ class TestMailSourcesAPI:
         db_session.add(MailSource(name="Disabled", method="IMAP", enabled=False))
         db_session.commit()
 
-        enabled = (
-            db_session.query(MailSource).filter(MailSource.enabled == True).all()  # noqa: E712
-        )
+        enabled = db_session.query(MailSource).filter(MailSource.enabled).all()
         assert len(enabled) == 2
         names = {s.name for s in enabled}
         assert "Enabled A" in names