uiform: clear foreground on blurred titles/options too

ThemeBase16 copies Focused into Blurred wholesale, so clearing the foreground only on Focused.Title/Group.Title/Focused.UnselectedOption left the Blurred variants pinned to base16 slots (title 8, unselected option 7). Inactive fields in multi-field forms (e.g. review --edit pickers) rendered with those pinned colors and couldn't invert with the terminal background.

Clear Blurred.Title and Blurred.UnselectedOption as well so inactive-field text inherits the terminal default, matching the buttons which already set both Focused and Blurred variants. Adds a regression test over the theme's blurred/focused/group foreground state for both dark and light.