Add menu item to clear configuration cache

[Copilot]

Adds Help → Clear Configuration Cache... menu item with confirmation dialog. Users can clear the current version's cache directory and optionally clear cache from previous Cura versions.

Implementation

• CuraActions.py: clearConfigurationCache(clear_all_versions) method

  • Removes cache/ from current data storage path via shutil.rmtree()
  • When clear_all_versions=True, scans parent directory for folders matching ^\d+\.\d+$ pattern and removes their cache/ subdirectories
  • Exception handling with user-facing Message dialogs

• Actions.qml: Registered clearConfigurationCache action

• HelpMenu.qml: Added menu item after "Open Cura Log File"

• Cura.qml: UM.Dialog with checkbox for previous versions option

Example Usage

# Clears only current version cache
CuraActions.clearConfigurationCache(clear_all_versions=False)

# Clears cache from /path/to/cura/5.0/cache, /path/to/cura/5.1/cache, etc.
CuraActions.clearConfigurationCache(clear_all_versions=True)

Version pattern validation prevents accidental deletion of non-Cura directories in the data storage root.

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.