fix(workflow): add csv/cities.csv to gzip+release upload (#1374) (#1385)

The export workflow was generating csv/cities.csv but not compressing
or uploading it, leaving downstream consumers without a stable URL for
the CSV cities export. All other formats (json, sql, xml, yml, sqlite,
sqlserver, geojson, toon) already gzip cities.X. This adds the missing
parallel for csv/cities.csv so it gets uploaded alongside the other
release assets at:

  https://github.com/dr5hn/countries-states-cities-database/releases/latest/download/csv-cities.csv.gz

Closes #1374

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: dr5hn

.github/workflows/export.yml

@@ -338,6 +338,10 @@ jobs:
 
           # CSV Files
           echo "📄 Compressing CSV files..."
+          if [ -f csv/cities.csv ]; then
+            gzip -9 -k -f csv/cities.csv
+            echo "  ✓ csv/cities.csv.gz"
+          fi
           if [ -f csv/translations.csv ]; then
             gzip -9 -k -f csv/translations.csv
             echo "  ✓ csv/translations.csv.gz"