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

Closes the JSON round-trip gap on the liquid catalog format
shipped this batch. --export-wliq-json emits all 14 scalar
fields (incl. 3-byte fog RGB) plus a dual int + name form for
liquidKind so hand-edits can use either representation.
--import-wliq-json accepts either form, falling back to the
int when both are present. Verified byte-identical round-trip
on all three preset emitters (starter / magical / hazardous).
716 documented CLI flags.

tools/editor/cli_arg_required.cpp

@@ -133,6 +133,7 @@ const char* const kArgRequired[] = {
     "--export-whol-json", "--import-whol-json",
     "--gen-liquids", "--gen-liquids-magical", "--gen-liquids-hazardous",
     "--info-wliq", "--validate-wliq",
+    "--export-wliq-json", "--import-wliq-json",
     "--gen-weather-temperate", "--gen-weather-arctic",
     "--gen-weather-desert", "--gen-weather-stormy",
     "--gen-zone-atmosphere",