- Added hierarchical comments pagination:
- Created new GraphQL query `load_comments_branch` for efficient loading of hierarchical comments
- Ability to load root comments with their first N replies
- Added pagination for both root and child comments
- Using existing `commented` field in `Stat` type to display number of replies
- Added special `first_replies` field to store first replies to a comment
- Optimized SQL queries for efficient loading of comment hierarchies
- Implemented flexible comment sorting system (by time, rating)
