- Replace custom semantic-ui dropdown component with standard HTML select element
- Simplify JavaScript by using native event listener instead of semantic-ui dropdown API
- Remove unnecessary dropdown initialization and selection setting code
- Maintain same functionality while reducing complexity and dependency on semantic-ui
- Relocate hardness dropdown from left to right side of filter controls
- Change form submission behavior to update URL parameters directly
- Preserve selected hardness value on page reload
- Remove page parameter when hardness changes to reset pagination
- Improve visual alignment and spacing in filter interface
- Added hardness filter dropdown in problemset UI with options 1-8
- Implemented server-side hardness parameter validation and filtering
- Refactored query parameter handling to use $filter_params array
- Updated SQL queries to use parameter binding for both search and hardness filters
- Fixed pagination to include hardness parameter in URL
- Improved code organization by centralizing filter parameter management
