- Introduced a new module `holyday.py` to manage and display holidays based on the current date.
- Implemented an enumeration for months and a dictionary for holiday messages.
- Created a new UI file `settingDialog.ui` for user settings, including language and theme selection.
- Added checkboxes for showing holidays and enabling developer mode in the settings dialog.
- Changed the instance editor main window class name from "Instance" to "InstancesEditor" in the UI file.
- Updated the instance editor window title to "LCE Qt Launcher - Instances Editor" and added an application icon.
- Updated product and file version to "0.26.4.2" in main.py.
- Updated package version for "lce-qt-launcher" to "26.4.2a1" in uv.lock.
- Removed unused dependencies "term-image" from the project.