- add occurrence counting menu using StudentOccurrenceIndexFinder
- add student settings window for configuring search target
- display occurrence count and matching indices
- update current collection menu to delegate occurrence counting
- add search menu with filter configuration and result actions
- add support for AND and OR filter relations
- add range filters for group number, average grade, and record book number
- update current collection menu to delegate search operations
- add bubble and merge sort algorithm selection
- add SortStrategySelectionWindow
- apply selected strategy to normal and parity sorting
- use dedicated comparators for student fields
- remove obsolete EvenOnlyMergeSortStrategy
- update collection menu labels and TODO placeholders
- move MainMenu to the root ui package
- add CurrentCollectionMenu for current collection operations
- move sorting components under collection/sorting
- add CollectionFileSaveWindow for saving collections to file
- update imports and menu delegation
debug-version