Fix #1: SELECT FOR UPDATE on task_counter to prevent race condition

src/tracker/api/tasks.py

@@ -227,7 +227,9 @@ async def create_task(
     current_member: Member = Depends(get_current_member),
     db: AsyncSession = Depends(get_db),
 ):
-    result = await db.execute(select(Project).where(Project.slug == project_slug))
+    result = await db.execute(
+        select(Project).where(Project.slug == project_slug).with_for_update()
+    )
     project = result.scalar_one_or_none()
     if not project:
         raise HTTPException(404, "Project not found")