[ZhuchkaTriplesix]

Creating a connection wrote the row, then the password to the system keyring, and rolled the row back if that write threw. The creation paths did not catch it: the form closed, the connection was missing and nothing was shown. Editing a connection already showed a toast; creating did not.

• `saveNewConnection` (connection_creation_flow.dart) stores the row, and on failure logs the error type and stack with `debugPrint` and shows "The connection was not saved. …".
• Used by every creation path: the connections panel (add button, folder menu) and the four flows in `MainScreenDialogs` (form, URL, SQLite, hero).
• Not covered: the scratch connection of a file opened from the file manager and the demo playground; their own error handling is unchanged.

This surfaces the failure; it does not change why a save can fail. Reported on macOS beta 0.5.0-beta.1, where the cause is still unknown (the login-keychain fix #1586 is already in that build). With this build the real error appears in the toast and the log. Not run on a Mac.