Simplify interface

For the next release, it would be great if all the plugin settings were contained on one page, accessible from the sidebar.

1. Instead of having users "Save changes" on a page with empty fields in order to access information that's already been entered, combine these two pages into one. This would follow the pattern set in other plugins, where existing settings appear on the same page as the forms to add new settings:

1b. Alternatively, tabs would also provide access to the second page without having to save the first page:

2. Instead of having site footer settings in the plugin configuration page, remove the config page and incorporate the site footer settings into the other interface where existing projects display.
   2b. I think you can probably show the projects in a table with a column for "Remove" and a column for "Site footer" (checkboxes for each). I do like the labels/notices collapsed by default with a way to expand the table row, and I think we already do that in the items table ("Details" will expand each row) so that could probably work.

Start by reviewing the plugin configuration page, the sidebar entry, and the existing projects and items tables referenced in the issue. Decide between a combined page and tabs, then verify that existing settings, new-setting forms, removal controls, site-footer checkboxes, and expandable details are accessible without the current save-first flow.