feat: webui.py: now up to date with comfy config options, shows already downloaded models

[tazlin]

• This brings the webui.py module up to date with the available options in the comfy branch.
  • This includes the VRAM/RAM free options, and the new Scribe options.
• Also shows already downloaded models.
  • If AIWORKER_CACHE_HOME is set, that is used. Direct users which use this environment variable to set it before invoking.
  • Otherwise, the working directory (./) is checked for a 'nataili' folder.
  • This is a mild convenience feature for users who may want to minimize disk space, but potentially have historically run features such as dynamic models.