[FIX] Wrap set_user_organization in transaction.atomic + worktree skill safety

.claude/skills/worktree/SKILL.md

@@ -26,7 +26,10 @@ Create isolated worktrees for parallel development. Ends by providing commands t
    ```bash
    git fetch origin main
    mkdir -p "$(dirname "$WORKTREE_PATH")"
-   git worktree add -b "{branch}" "$WORKTREE_PATH" origin/main
+   # --no-track: do NOT set the new branch's upstream to origin/main.
+   # Without it, a later `git push -u origin {branch}` can be reported by
+   # the server as also fast-forwarding main, landing commits on main.
+   git worktree add --no-track -b "{branch}" "$WORKTREE_PATH" origin/main
    ```
 
 4. **Copy config files**

backend/account_v2/authentication_controller.py

@@ -3,6 +3,7 @@
 
 from django.conf import settings
 from django.contrib.auth import logout as django_logout
+from django.db import transaction
 from django.db.utils import IntegrityError
 from django.http import HttpRequest
 from django.middleware import csrf
@@ -101,7 +102,7 @@
                 request=request, backend=backend
             )
         except Exception as ex:
             logger.error(f"Error while handling authorization callback: {ex}")
             return redirect("/error")
 
     def user_organizations(self, request: Request) -> Any:
@@ -163,6 +164,7 @@
 
         return response
 
+    @transaction.atomic
     def set_user_organization(self, request: Request, organization_id: str) -> Response:
         user: User = request.user
         new_organization = False