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.

tests/testthat/test_theme.R

@@ -226,6 +226,21 @@ test_that("theme_civilytics_dark inherits grid parameter", {
   expect_s3_class(th$panel.grid.major.y, "element_line")
 })
 
+test_that("theme_civilytics_dark uses readable subtitle and caption colors", {
+  th <- theme_civilytics_dark()
+  # Subtitle should use navy_200, not the dark ink_2
+  expect_equal(th$plot.subtitle$colour, unname(civilytics_colors["navy_200"]))
+  # Caption should use navy_300, not the dark ink_3
+  expect_equal(th$plot.caption$colour, unname(civilytics_colors["navy_300"]))
+})
+
+test_that("theme_civilytics_dark uses readable axis text colors", {
+  th <- theme_civilytics_dark()
+  expect_equal(th$axis.text$colour, unname(civilytics_colors["navy_200"]))
+  expect_equal(th$axis.title.x$colour, unname(civilytics_colors["navy_300"]))
+  expect_equal(th$axis.title.y$colour, unname(civilytics_colors["navy_300"]))
+})
+
 # --- theme_civilytics_slide --------------------------------------------------
 
 test_that("theme_civilytics_slide returns a complete ggplot2 theme", {
@@ -253,6 +268,90 @@ test_that("theme_civilytics_slide applies to a ggplot without error", {
   expect_no_error(ggplot_build(p))
 })
 
+# --- theme_civilytics_map ----------------------------------------------------
+
+test_that("theme_civilytics_map returns a complete theme", {
+  th <- theme_civilytics_map()
+  expect_s3_class(th, "theme")
+  expect_true(attr(th, "complete"))
+})
+
+test_that("theme_civilytics_map suppresses axes and gridlines", {
+  th <- theme_civilytics_map()
+  expect_s3_class(th$axis.line.x, "element_blank")
+  expect_s3_class(th$axis.text, "element_blank")
+  expect_s3_class(th$axis.ticks, "element_blank")
+  expect_s3_class(th$axis.title.x, "element_blank")
+  expect_s3_class(th$axis.title.y, "element_blank")
+  expect_s3_class(th$panel.grid.major.x, "element_blank")
+  expect_s3_class(th$panel.grid.major.y, "element_blank")
+})
+
+test_that("theme_civilytics_map preserves title and caption elements", {
+  th <- theme_civilytics_map()
+  expect_s3_class(th$plot.title, "element_text")
+  expect_s3_class(th$plot.subtitle, "element_text")
+  expect_s3_class(th$plot.caption, "element_text")
+})
+
+test_that("theme_civilytics_map applies to a ggplot without error", {
+  p <- ggplot(mpg, aes(displ, hwy)) +
+    geom_point() +
+    theme_civilytics_map()
+  expect_no_error(ggplot_build(p))
+})
+
+# --- theme_civilytics_dark_map -----------------------------------------------
+
+test_that("theme_civilytics_dark_map returns a complete theme", {
+  th <- theme_civilytics_dark_map()
+  expect_s3_class(th, "theme")
+  expect_true(attr(th, "complete"))
+})
+
+test_that("theme_civilytics_dark_map suppresses axes on dark background", {
+  th <- theme_civilytics_dark_map()
+  expect_s3_class(th$axis.line.x, "element_blank")
+  expect_s3_class(th$axis.text, "element_blank")
+  expect_s3_class(th$axis.ticks, "element_blank")
+  expect_equal(th$plot.background$fill, unname(civilytics_colors["navy_700"]))
+})
+
+test_that("theme_civilytics_dark_map applies to a ggplot without error", {
+  p <- ggplot(mpg, aes(displ, hwy)) +
+    geom_point() +
+    theme_civilytics_dark_map()
+  expect_no_error(ggplot_build(p))
+})
+
+# --- theme_civilytics_slide_map ----------------------------------------------
+
+test_that("theme_civilytics_slide_map returns a complete theme", {
+  th <- theme_civilytics_slide_map()
+  expect_s3_class(th, "theme")
+  expect_true(attr(th, "complete"))
+})
+
+test_that("theme_civilytics_slide_map has larger font and suppressed axes", {
+  th <- theme_civilytics_slide_map()
+  th_base <- theme_civilytics_map()
+  expect_gt(th$text$size, th_base$text$size)
+  expect_s3_class(th$axis.line.x, "element_blank")
+  expect_s3_class(th$axis.text, "element_blank")
+})
+
+test_that("theme_civilytics_slide_map has transparent background by default", {
+  th <- theme_civilytics_slide_map()
+  expect_true(is.na(th$plot.background$fill))
+})
+
+test_that("theme_civilytics_slide_map applies to a ggplot without error", {
+  p <- ggplot(mpg, aes(displ, hwy)) +
+    geom_point() +
+    theme_civilytics_slide_map()
+  expect_no_error(ggplot_build(p))
+})
+
 # --- make_logo_grob ----------------------------------------------------------
 
 test_that("make_logo_grob returns a gg object for all type/variant combos", {