Add unified sortUsing() method to simplify sorting logic

[arukompas]

Summary

• Introduces unified sortUsing(SortingMethod, SortingOrder) method to both LogFileCollection and LogFolderCollection
• Simplifies controller sorting logic from ~30 lines of nested if/else to single-line calls
• All existing sorting methods remain and delegate to the new method (backwards compatible)
• Controllers updated to use new simplified API

Changes

• LogFileCollection: Added sortUsing() method, refactored existing methods to use it
• LogFolderCollection: Added sortUsing() method, refactored existing methods to use it
• FilesController: Simplified sorting logic (lines 21-34 → line 21)
• FoldersController: Simplified sorting logic (lines 26-56 → lines 26-28)
• Tests: Added 8 new tests for sortUsing() method

Test plan

• All 281 existing tests pass
• 8 new unit tests added for sortUsing() method
• No breaking changes - all existing public methods remain functional
• Code formatted with Laravel Pint