Add 'Replace' action to File menu

[PCSmithy]

Summary

• Adds a File > Replace menu action (Ctrl+Shift+O) that swaps the current MDF file while preserving the display configuration (plot windows, selected channels, window geometry, etc.)
• This streamlines the workflow of comparing multiple MDF files that share the same signal layout — no need to manually re-open a .dspf config after switching files

Implementation

src/asammdf/gui/widgets/main.py:

• New menu action "Replace" added to the File menu after "Open folder", reusing the existing open icon
• New replace_file() method that:
  1. Captures the current display config via FileWidget.to_config()
  2. Shows a single-file open dialog
  3. Closes the old tab
  4. Opens the new file with display_file=config to restore the layout
  5. Inserts the new tab at the same position

Guard clauses handle edge cases: no file open, not in single-file mode, user cancels dialog.

Test coverage

test/asammdf/gui/widgets/Shortcuts/test_MainWindow_Shortcuts.py — 4 new test cases in TestReplaceFile:

Test	What it verifies
test_replace_file_preserves_tab_position	Tab count stays at 1, tab label/tooltip update to new file
test_replace_file_preserves_display_config	Plot sub-window with selected channels is recreated on the new file
test_replace_file_no_op_when_no_file_open	Replace is a no-op when no tabs are open (dialog never shown)
test_replace_file_no_op_when_dialog_cancelled	Original tab is unchanged when user cancels the file dialog

All 4 tests pass.

Test plan

• Open an MDF file, select signals, create plot windows
• File > Replace (or Ctrl+Shift+O), pick a different MDF with same signal names
• Verify: new file loaded, same plot windows appear with data from the new file, tab position preserved
• Test: Replace with no file open (should no-op)
• Test: Cancel the dialog (should no-op)
• Test: Replace with a file that has different signals (should show partial data gracefully)

[danielhrisca]

Hello Patrick, thanks for the PR. I wish I had the patience and discipline to write PR descriptions such as yours.

[PCSmithy]

Hello Patrick, thanks for the PR. I wish I had the patience and discipline to write PR descriptions such as yours.

haha, thanks, I try to make things easy to review.

I think I've fixed the failed tests (had to do with the unsaved-config popup). I'm not sure how to re-trigger the CI checks on the PR. Could you re-trigger those by chance?

[danielhrisca]

thanks !