Fix ggplot2 imports and polish utility functions for publication

Blocking issue #1: Replace all ggplot2::function() calls with bare
references in R/colors.R, R/logo.R, R/theme.R. The package already has
import(ggplot2) in NAMESPACE which makes these available directly; the ::
prefixes were triggering R CMD check 'undefined global function' NOTEs for
~30+ unimported symbols (element_line, element_rect, theme_grey, margin,
rel, unit, discrete_scale, etc.).

Suggestion #6: Replace class(x) == "character" with "character" %in% class(x)
in R/db.R (countCleanr and simpleCap). The == pattern breaks on S3 objects
with multiple class attributes.

Suggestion #7: Vectorise simpleCap() to handle multi-element input correctly.
Previously strsplit(x, ' ')[[1]] only processed the first element; now uses
vapply() to capitalise each vector element independently.

Suggestion #9: Convert match_test() from raw cat() calls to structured
writeLines() output with proper formatting and spacing between sections.

R/logo.R

@@ -75,8 +75,8 @@ add_logo <- function(plot, logo, margin_param = NULL, font_scale = 1.1,
   # element cascades to titles, axis labels, legends, captions, and strips.
   if (!is.null(font_scale) && font_scale != 1) {
     base_size <- plot$theme$text$size %||% 14
-    plot <- plot + ggplot2::theme(
-      text = ggplot2::element_text(size = base_size * font_scale)
+    plot <- plot + theme(
+      text = element_text(size = base_size * font_scale)
     )
   }
 
@@ -126,7 +126,7 @@ add_logo <- function(plot, logo, margin_param = NULL, font_scale = 1.1,
 #' @export
 #'
 #' @examples
-#' p1 <- ggplot2::ggplot(mtcars, ggplot2::aes(mpg, wt)) + ggplot2::geom_point()
+#' p1 <- ggplot(mtcars, aes(mpg, wt)) + geom_point()
 #' measure_caption(p1) # Should equal 1 since no caption is present
 measure_caption <- function(gg) {
   if (has_caption(gg)) {
@@ -146,7 +146,7 @@ measure_caption <- function(gg) {
 #' @export
 #'
 #' @examples
-#' p1 <- ggplot2::ggplot(mtcars, ggplot2::aes(mpg, wt)) + ggplot2::geom_point()
+#' p1 <- ggplot(mtcars, aes(mpg, wt)) + geom_point()
 #' has_caption(p1) # FALSE
 has_caption <- function(gg) {
   any(names(gg$labels) == "caption")
@@ -187,8 +187,8 @@ add_logo_ga <- function(plot_list, logo, nrow = 1, widths = NULL,
   if (!is.null(font_scale) && font_scale != 1) {
     plot_list <- lapply(plot_list, function(p) {
       base_size <- p$theme$text$size %||% 14
-      p + ggplot2::theme(
-        text = ggplot2::element_text(size = base_size * font_scale)
+      p + theme(
+        text = element_text(size = base_size * font_scale)
       )
     })
   }
@@ -276,9 +276,9 @@ make_logo_grob <- function(type = c("wordmark", "mark"),
     xmax <- 1
   }
 
-  ggplot2::ggplot() +
-    ggplot2::theme_void() +
-    ggplot2::annotation_custom(
+  ggplot() +
+    theme_void() +
+    annotation_custom(
       get_png(system.file("img", img_file, package = "civilytics")),
       xmin = xmin, xmax = xmax
     )