feat(editor): add WHOL JSON round-trip (export/import sidecar)

Closes the JSON round-trip gap on the holiday catalog format
shipped last batch. --export-whol-json emits all 13 scalar
fields plus dual int + name forms for holidayKind and
recurrence so hand-edits can use either representation.
--import-whol-json accepts either form, falling back to the
int when both are present. Verified byte-identical round-trip
on all three preset emitters (starter / weekly / special).
709 documented CLI flags.

tools/editor/cli_arg_required.cpp

@@ -130,6 +130,7 @@ const char* const kArgRequired[] = {
     "--export-wvhc-json", "--import-wvhc-json",
     "--gen-holidays", "--gen-holidays-weekly", "--gen-holidays-special",
     "--info-whol", "--validate-whol",
+    "--export-whol-json", "--import-whol-json",
     "--gen-weather-temperate", "--gen-weather-arctic",
     "--gen-weather-desert", "--gen-weather-stormy",
     "--gen-zone-atmosphere",