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/make_logo_grob.Rd

@@ -4,22 +4,26 @@
 \alias{make_logo_grob}
 \title{Get a Civilytics Logo grob}
 \usage{
-make_logo_grob(variant = c("light", "dark"))
+make_logo_grob(type = c("wordmark", "mark"), variant = c("light", "dark"))
 }
 \arguments{
-\item{variant}{Character. `"light"` (default) uses the standard dark logo
-suitable for light backgrounds. `"dark"` uses the white logo suitable for
-dark backgrounds (pairs with [theme_civilytics_dark()]).}
+\item{type}{Character. `"wordmark"` (default) uses the full wordmark.
+`"mark"` uses the compact C-pulse icon only.}
+
+\item{variant}{Character. `"light"` (default) uses the dark logo for light
+backgrounds. `"dark"` uses the reverse (light) logo for dark backgrounds
+(pairs with [theme_civilytics_dark()]).}
 }
 \value{
 A ggplot object (class `"gg"`) containing the logo grob.
 }
 \description{
 Returns a ggplot object containing the Civilytics logo as a rasterGrob,
-ready to compose with plots via [add_logo()] or [add_logo_ga()].
+ready to compose with plots via [add_logo()], [add_logo_ga()], or the
+pipe-friendly [civilytics_logo()].
 }
 \examples{
-logo       <- make_logo_grob()           # light background
-logo_dark  <- make_logo_grob("dark")     # dark background
+logo <- make_logo_grob()                          # wordmark, light
+logo <- make_logo_grob("mark", "dark")            # mark, dark
 class(logo)  # "gg" "ggplot"
 }