style: apply ruff formatting to source and test files

app/application/use_cases/create_post.py

@@ -27,9 +27,7 @@ class CreatePostUseCase:
 
         # Check if slug already exists
         if await self._post_repo.slug_exists(slug.value):
-            raise AlreadyExistsException(
-                f"Post with slug '{slug.value}' already exists"
-            )
+            raise AlreadyExistsException(f"Post with slug '{slug.value}' already exists")
 
         # Create domain entity
         post = Post.create(

app/application/use_cases/list_posts.py

@@ -38,9 +38,7 @@ class ListPostsUseCase:
         offset: int | None = None,
     ) -> list[PostResponseDTO]:
         """Get posts by author."""
-        posts = await self._post_repo.get_by_author(
-            author_id, limit=limit, offset=offset
-        )
+        posts = await self._post_repo.get_by_author(author_id, limit=limit, offset=offset)
         return [self._map_to_dto(post) for post in posts]
 
     async def by_tag(