Read JSON files under palettes_dir/, validate content, and return a
structured list of palettes. Used by data-raw/palettes.R to build
the package dataset via usethis::use_data().
Examples
# \donttest{
compile_palettes(
palettes_dir = system.file("extdata", "palettes", package = "evanverse")
)
#> ✔ Compiled 93 palettes: Sequential=11, Diverging=7, Qualitative=75
# }
