Version 1.6.0
* Bumped the target SDK version from 34 (Upside-down Cake)
  to 35 (Vanilla Ice Cream).
* Fixed an issue where hardware configuration changes such as
  rotating the screen would cause all edits in progress to be lost.
* Fixed a bug where the app would "forget" the user's last selected
  category filter when restarting (going back to All categories).
* Replaced all Service classes with equivalent Workers.  This
  allows them to be tested independently of the application.
* Refactored the importer to merge note records as they
  are read in from the backup file, which allows it to
  handle much larger data sets without using too much memory.
* Added a scroll bar to the note editor.  The scroll bar
  is optional and can be configured in the app settings.
* Added the ability to export an individual note to a plain text file and to
  insert text files into a note.  Addresses feature request #1 from GitHub.
