Minor improvements

[hollowstrawberry]

• Added a nice embed for image parameters which will be sent ephemerally with the 🔎 button. The embed will have its own button to send the full parameters in code block form, ephemeral again. This is overkill but I ported it over mostly intact from my stable diffusion image scanner cog. You could edit it to make it not ephemeral if you want.
• Will check for permissions of the "imagine" command before running the slash command. This lets you control who can use the command and where, with the permissions cog for normal commands, without having to edit the integrations menu of servers.
• Better error messages for the user.
• The negative prompt config command was only catching the first word.
• Increase max width and height because of SDXL.

[zhaobenny]

Thanks! 🎉

The negative prompt config command was only catching the first word.

oof, that was an oversight