I made some additions and refinements. There are a few minor things that still could be added or cleaned up, but I don't really see much purpose unless there was a need.
Replaced model type selection in Download Tab with path input.
Added directory dropdown memory for most recently selected path. (Maybe a bit too confusing to use sometimes?)
Separated mouse and keyboard path dropdown highlighting/selection.
The server now sends thumbnails to the model grid, but will still be full-sized in the Model Info View.
Downloads from Civitai now attempt to get the full-sized preview (as the model API currently sends scaled-down image urls), but there may be a bug with the image API, so most of the time you may have to manually add the image urls if you want the full-sized image previews.
The browser now prompts the user to Save or Discard changes to notes on close. However, there will not be an alert when closing/reloading the browser tab/window itself.
100% support for dragging models onto nodes/node input text where the model is a valid input. However, note that currently you need to reload the webpage if model was just moved or added and not in a node input's dropdown.
Fixed topbar buttons to display correctly with narrow (mobile) screens.
Optional setting in Settings Tab (disabled by default) to download model description as notes.
Added and tested lazy-loading previews in model grid.
Changed 'no-preview' image to hand-made image.
Added browser window alerts on expected server failures.
I made some additions and refinements. There are a few minor things that still could be added or cleaned up, but I don't really see much purpose unless there was a need.
.preview.<extension>preview naming convention used by stable_diffusion_webui_civitai_helper. (https://github.com/hayden-fr/ComfyUI-Model-Manager/issues/5).