--opt-split-attention now on by default for torch.cuda, off for others (cpu and MPS; because the option does not work there according to reports)

This reverts commit 8d1d64f9.

The following file patterns are invalid on Windows.
- Begin or end with the ASCII Space (0x20)
- End with the ASCII Period (0x2E)

For example, if `[prompt_spaces]` is specified as the directory name pattern, sometimes file saving may fail.

add a setting for lightbox max size images
use setting for lightbox max size images late to let user change it and see results