Converts a district name to a lowercase, hyphenated slug suitable for URLs and entity linking. Strips common suffixes like "School District", "Public Schools", etc. When duplicate slugs exist, appends the district_id to disambiguate.
Examples
slugify_district("Denver Public Schools")
#> [1] "denver"
# "denver"
slugify_district("Colorado Springs School District 11")
#> [1] "colorado-springs"
# "colorado-springs"
slugify_district(c("Liberty", "Liberty"), c("1234", "5678"))
#> [1] "liberty-1234" "liberty-5678"
# c("liberty-1234", "liberty-5678")