feat: add like/unlike toggle on blog posts with per-user tracking

- PostLike domain entity (post_id, liked_by) with BaseEntity integration
- Post entity: add like_count field (default 0) and to_dict serialization
- PostRepository interface: add get_like, add_like, remove_like methods
- TogglePostLikeUseCase: toggle logic (like → unlike, unlike → like)
- PostResponseDTO/PostResponseSchema: add like_count field
- PostLikeORM model with FK to posts and cascade delete
- SQLAlchemyPostRepository: implement like query/add/remove with ORM mapping
- DI provider registration for TogglePostLikeUseCase
- API endpoint POST /api/v1/posts/{id}/like (auth required)
- Unit tests: PostLike entity, Post.like_count, TogglePostLikeUseCase (7 tests)
- API tests: POST /api/v1/posts/{id}/like (4 tests)
- Test model files: FEATURE_LIKES.md, TEST_MODEL.md updated

app/presentation/api/v1/posts.py

@@ -20,6 +20,7 @@ from app.presentation.api.deps import (
     GetPostDep,
     ListPostsDep,
     PublishPostDep,
+    ToggleLikeDep,
     UpdatePostDep,
 )
 from app.presentation.schemas import (
@@ -344,3 +345,30 @@ async def unpublish_post(
     """
     result = await use_case.unpublish(post_id, current_user_id, role)
     return PostResponseSchema(**result.__dict__)
+
+
+@router.post(
+    "/{post_id}/like",
+    response_model=PostResponseSchema,
+    summary="Toggle like on a post",
+)
+async def toggle_like(
+    post_id: UUID,
+    use_case: ToggleLikeDep,
+    current_user_id: CurrentUserDep,
+) -> PostResponseSchema:
+    """Toggle like/unlike on a post.
+
+    If the user already liked the post, the like is removed (unlike).
+    Otherwise, a new like is added.
+
+    Args:
+        post_id: Unique identifier of the post.
+        use_case: TogglePostLikeUseCase dependency.
+        current_user_id: Authenticated user ID.
+
+    Returns:
+        PostResponseSchema with updated like_count.
+    """
+    result = await use_case.execute(post_id, current_user_id)
+    return PostResponseSchema(**result.__dict__)