fix: wrap create_default_labels in transaction.atomic() savepoint to prevent PostgreSQL transaction abort (#11484) (#11490)

When the plugin registry reloads during an active HTTP request,
create_default_labels() raises ValidationError on duplicate template
inserts. On PostgreSQL this aborts the entire outer atomic() block,
causing TransactionManagementError on all stock operations in that request.

Fixes #11469


(cherry picked from commit a964d6682e)

Co-authored-by: tigger2000ttfn <tigger2000ttfn@gmail.com>
Co-authored-by: Oliver <oliver.henry.walters@gmail.com>

src/backend/InvenTree/report/apps.py

@@ -7,6 +7,7 @@ from django.apps import AppConfig
 from django.core.exceptions import AppRegistryNotReady, ValidationError
 from django.core.files.base import ContentFile
 from django.core.files.storage import default_storage
+from django.db import transaction
 from django.db.utils import IntegrityError, OperationalError, ProgrammingError
 
 import structlog
@@ -160,6 +161,7 @@ class ReportConfig(AppConfig):
             # Otherwise, create a new entry
             try:
                 # Create a new entry
+                with transaction.atomic():
                     report.models.LabelTemplate.objects.create(
                         **template, template=self.file_from_template('label', filename)
                     )