feat: add map theme variants and fix dark theme text readability

Add theme_civilytics_map(), theme_civilytics_dark_map(), and
theme_civilytics_slide_map() for choropleths — suppress axes, ticks,
gridlines, and axis labels while preserving titles, captions, and legends.

Fix subtitle, caption, and axis text colors in theme_civilytics_dark()
which were inheriting dark ink_2/ink_3 values meant for light backgrounds,
making them hard to read on navy. Now uses navy_200/navy_300 instead.

R/theme.R

@@ -355,7 +355,27 @@ theme_civilytics_dark <- function(
     strip_color  = strip_color,
     grid         = grid,
     paper_bg     = paper_bg
-  )
+  ) +
+    # The base theme hardcodes ink_2/ink_3 for subtitle/caption, which are
+    # dark colors meant for light backgrounds.  Override with lighter values
+    # so text remains readable on the navy background.
+    ggplot2::theme(
+      plot.subtitle = ggplot2::element_text(
+        color = unname(civilytics_colors["navy_200"])
+      ),
+      plot.caption = ggplot2::element_text(
+        color = unname(civilytics_colors["navy_300"])
+      ),
+      axis.text = ggplot2::element_text(
+        color = unname(civilytics_colors["navy_200"])
+      ),
+      axis.title.x = ggplot2::element_text(
+        color = unname(civilytics_colors["navy_300"])
+      ),
+      axis.title.y = ggplot2::element_text(
+        color = unname(civilytics_colors["navy_300"])
+      )
+    )
 }
 
 
@@ -417,3 +437,186 @@ theme_civilytics_slide <- function(
       plot.margin = ggplot2::margin(24, 24, 24, 24)
     )
 }
+
+
+# -- Map themes ----------------------------------------------------------------
+
+#' Shared map-theme overrides
+#'
+#' Strips away axes, ticks, gridlines, and axis titles/labels — the elements
+#' that are meaningless on a choropleth or spatial plot.
+#'
+#' @return A partial ggplot2 [ggplot2::theme()] object.
+#' @keywords internal
+.map_theme_extras <- function() {
+  ggplot2::theme(
+    axis.line    = ggplot2::element_blank(),
+    axis.line.x  = ggplot2::element_blank(),
+    axis.line.y  = ggplot2::element_blank(),
+    axis.text    = ggplot2::element_blank(),
+    axis.text.x  = ggplot2::element_blank(),
+    axis.text.y  = ggplot2::element_blank(),
+    axis.ticks   = ggplot2::element_blank(),
+    axis.ticks.length = ggplot2::unit(0, "pt"),
+    axis.title.x = ggplot2::element_blank(),
+    axis.title.y = ggplot2::element_blank(),
+    panel.grid.major.x = ggplot2::element_blank(),
+    panel.grid.major.y = ggplot2::element_blank(),
+    panel.grid.minor   = ggplot2::element_blank()
+  )
+}
+
+
+#' Map-friendly Civilytics ggplot2 theme
+#'
+#' Variant of [theme_civilytics()] for choropleths and spatial plots.
+#' Suppresses axes, axis labels, ticks, and gridlines while keeping the
+#' Civilytics brand typography, colors, and plot-level elements (title,
+#' subtitle, caption, legend).
+#'
+#' @inheritParams theme_civilytics
+#'
+#' @return A complete ggplot2 [ggplot2::theme()] object.
+#' @export
+#'
+#' @examples
+#' \dontrun{
+#' library(ggplot2)
+#' # With sf data:
+#' ggplot(map_data) +
+#'   geom_sf(aes(fill = value)) +
+#'   scale_fill_civilytics_c("seq_navy") +
+#'   theme_civilytics_map()
+#' }
+theme_civilytics_map <- function(
+    font_size    = 14,
+    font_family  = CV_FONT_SANS,
+    title_family = CV_FONT_DISPLAY,
+    line_size    = 0.5,
+    rel_small    = 12 / 14,
+    rel_tiny     = 11 / 14,
+    rel_large    = 20 / 14,
+    ink          = unname(civilytics_colors["ink"]),
+    paper        = unname(civilytics_colors["paper"]),
+    accent       = unname(civilytics_colors["ember_600"]),
+    strip_color  = unname(civilytics_colors["paper_2"]),
+    paper_bg     = TRUE) {
+
+  theme_civilytics(
+    font_size    = font_size,
+    font_family  = font_family,
+    title_family = title_family,
+    line_size    = line_size,
+    rel_small    = rel_small,
+    rel_tiny     = rel_tiny,
+    rel_large    = rel_large,
+    ink          = ink,
+    paper        = paper,
+    accent       = accent,
+    strip_color  = strip_color,
+    grid         = "none",
+    paper_bg     = paper_bg
+  ) + .map_theme_extras()
+}
+
+
+#' Dark map-friendly Civilytics ggplot2 theme
+#'
+#' Variant of [theme_civilytics_dark()] for choropleths and spatial plots.
+#' Suppresses axes, axis labels, ticks, and gridlines on a dark navy
+#' background. Pair with `make_logo_grob(variant = "dark")`.
+#'
+#' @inheritParams theme_civilytics_dark
+#'
+#' @return A complete ggplot2 [ggplot2::theme()] object.
+#' @export
+#'
+#' @examples
+#' \dontrun{
+#' library(ggplot2)
+#' ggplot(map_data) +
+#'   geom_sf(aes(fill = value)) +
+#'   scale_fill_civilytics_c("seq_ember") +
+#'   theme_civilytics_dark_map()
+#' }
+theme_civilytics_dark_map <- function(
+    font_size    = 14,
+    font_family  = CV_FONT_SANS,
+    title_family = CV_FONT_DISPLAY,
+    line_size    = 0.5,
+    rel_small    = 12 / 14,
+    rel_tiny     = 11 / 14,
+    rel_large    = 20 / 14,
+    ink          = unname(civilytics_colors["paper"]),
+    paper        = unname(civilytics_colors["navy_700"]),
+    accent       = unname(civilytics_colors["ember_400"]),
+    strip_color  = unname(civilytics_colors["navy_600"]),
+    paper_bg     = TRUE) {
+
+  theme_civilytics_dark(
+    font_size    = font_size,
+    font_family  = font_family,
+    title_family = title_family,
+    line_size    = line_size,
+    rel_small    = rel_small,
+    rel_tiny     = rel_tiny,
+    rel_large    = rel_large,
+    ink          = ink,
+    paper        = paper,
+    accent       = accent,
+    strip_color  = strip_color,
+    grid         = "none",
+    paper_bg     = paper_bg
+  ) + .map_theme_extras()
+}
+
+
+#' Slide-friendly map Civilytics ggplot2 theme
+#'
+#' Variant of [theme_civilytics_slide()] for choropleths and spatial plots
+#' on slides. Combines the larger base font and transparent background of
+#' the slide theme with suppressed axes, ticks, and gridlines.
+#'
+#' @inheritParams theme_civilytics_slide
+#'
+#' @return A complete ggplot2 [ggplot2::theme()] object.
+#' @export
+#'
+#' @examples
+#' \dontrun{
+#' library(ggplot2)
+#' ggplot(map_data) +
+#'   geom_sf(aes(fill = value)) +
+#'   scale_fill_civilytics_c("seq_navy") +
+#'   theme_civilytics_slide_map()
+#' }
+theme_civilytics_slide_map <- function(
+    font_size    = 18,
+    font_family  = CV_FONT_SANS,
+    title_family = CV_FONT_DISPLAY,
+    line_size    = 0.5,
+    rel_small    = 12 / 14,
+    rel_tiny     = 11 / 14,
+    rel_large    = 20 / 14,
+    ink          = unname(civilytics_colors["ink"]),
+    paper        = unname(civilytics_colors["paper"]),
+    accent       = unname(civilytics_colors["ember_600"]),
+    strip_color  = unname(civilytics_colors["paper_2"]),
+    paper_bg     = FALSE) {
+
+  theme_civilytics_slide(
+    font_size    = font_size,
+    font_family  = font_family,
+    title_family = title_family,
+    line_size    = line_size,
+    rel_small    = rel_small,
+    rel_tiny     = rel_tiny,
+    rel_large    = rel_large,
+    ink          = ink,
+    paper        = paper,
+    accent       = accent,
+    strip_color  = strip_color,
+    grid         = "none",
+    paper_bg     = paper_bg
+  ) + .map_theme_extras()
+}