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

Closes the JSON round-trip gap on the companion pet catalog
format shipped last batch. --export-wcmp-json emits all 9
scalar fields plus dual int + name forms for companionKind
(8 values) / rarity (4 values) / factionRestriction (3 values)
so hand-edits can use either representation.
--import-wcmp-json accepts either form, falling back to the
int when both are present. Verified byte-identical round-trip
on all three preset emitters (starter / rare / faction). 784
documented CLI flags.

tools/editor/cli_arg_required.cpp

@@ -162,6 +162,7 @@ const char* const kArgRequired[] = {
     "--export-wgtp-json", "--import-wgtp-json",
     "--gen-cmp", "--gen-cmp-rare", "--gen-cmp-faction",
     "--info-wcmp", "--validate-wcmp",
+    "--export-wcmp-json", "--import-wcmp-json",
     "--gen-weather-temperate", "--gen-weather-arctic",
     "--gen-weather-desert", "--gen-weather-stormy",
     "--gen-zone-atmosphere",