* fix: name an untitled design after its file on save and open Design tabs all read "Untitled" because a design's name only ever came from file.new. Saving a design still under the default name now names it after the file (bracket.solidcraft -> "bracket"), and opening a file whose stored name is the default shows its file name. Names chosen by the user are kept. The rename is part of the save, so it is not an undo step and does not leave the design marked as changed. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01HWLPLy7ug7URSK5WybjRNa * test: expect the file's name after saving an untitled design Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01HWLPLy7ug7URSK5WybjRNa --------- Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>