feat: rebrand logos with wordmark/mark variants and pipe-friendly API

- Replace old civilytics_logo.png/white.png/jpg/pdf with new rebrand
  assets: civilytics-wordmark.png, civilytics-wordmark-reverse.png,
  civilytics-mark.png, civilytics-mark-reverse.png (all transparent bg)
- make_logo_grob() now accepts type = c("wordmark", "mark") alongside
  variant = c("light", "dark") for 4 combinations
- New civilytics_logo() pipe-friendly convenience function:
    ggplot(df, aes(x, y)) + geom_point() + theme_civilytics() |>
      civilytics_logo()
  R's |> has lower precedence than +, so the full ggplot chain pipes
  through without parentheses
- Remove old icon/favicon assets no longer used
- Wrap showtext-dependent examples in \dontrun{} to prevent R CMD check
  failures in headless PostScript environments

man/civilytics-package.Rd

@@ -19,10 +19,5 @@ Useful links:
 \author{
 \strong{Maintainer}: Jared E. Knowles \email{jared@civilytics.com}
 
-Authors:
-\itemize{
-  \item Jared E. Knowles \email{jared@civilytics.com}
-}
-
 }
 \keyword{internal}