- Add FileChooser and file_creation to block-editor-plugin, replacing four
  hand-rolled copies in the audio, game module, image and PDF editors.
- Add FileFilter::new so filters no longer map string slices by hand.
- Reuse block-ui's datetime helpers in version_control_data and calendar.
- Move the duplicated instruction formatter into logicgame as Display.


Claude-Session: https://claude.ai/code/session_01V62wS6nuyBDobeqcX4YkMV

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: be3-merge-queue[bot] <332166134+be3-merge-queue[bot]@users.noreply.github.com>