Implement a new feature that generates thumbnail previews for image uploads. The change adds a dedicated preview handler that processes uploaded images, creates scaled-down versions, and stores them alongside the original files. This enables faster loading of image galleries and list views without fetching full-resolution assets.
- Added BlockingService class with methods for managing blocked users and content
- Integrated blocking checks into message delivery pipeline to filter blocked senders
- Added database migration for blocked_users table with user_id and target_id columns
The traversal function and its associated helper methods have been deleted from the pathfinding module, simplifying the codebase by eliminating dead code that was no longer referenced by any active components.
