feat: add position argument to civilytics_logo() for corner placement

Supports "bottom-right" (default), "bottom-left", "top-right", and
"top-left". The position controls both horizontal alignment of the logo
grob and whether it is placed above or below the plot.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

man/add_logo.Rd

@@ -4,7 +4,13 @@
 \alias{add_logo}
 \title{Add a logo to a ggplot2 object}
 \usage{
-add_logo(plot, logo, margin_param = NULL, font_scale = 1.1)
+add_logo(
+  plot,
+  logo,
+  margin_param = NULL,
+  font_scale = 1.1,
+  position = c("bottom-right", "bottom-left", "top-right", "top-left")
+)
 }
 \arguments{
 \item{plot}{a ggplot2 grob}
@@ -17,6 +23,10 @@ add_logo(plot, logo, margin_param = NULL, font_scale = 1.1)
 sizes before composing the plot with the logo. Default `1.1` inflates
 text by ~10 \% to compensate for the viewport shrinkage caused by
 [gridExtra::arrangeGrob()]. Set to `1` to disable.}
+
+\item{position}{Character. Corner placement for the logo: `"bottom-right"`
+(default), `"bottom-left"`, `"top-right"`, or `"top-left"`. Controls
+whether the logo is placed above or below the plot.}
 }
 \value{
 a grob with a logo attached to it ready to plot