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

Closes the JSON round-trip gap on the world-state UI catalog
format shipped last batch. --export-wwui-json emits all 11
scalar fields plus dual int + name forms for displayKind and
panelPosition so hand-edits can use either representation.
--import-wwui-json accepts either form, falling back to the
int when both are present, and defaults iconColorRGBA to
0xFFFFFFFF (opaque white) when omitted. Verified
byte-identical round-trip on all three preset emitters
(starter / wintergrasp / dungeon). 740 documented CLI flags.

tools/editor/cli_arg_required.cpp

@@ -143,6 +143,7 @@ const char* const kArgRequired[] = {
     "--export-wsvk-json", "--import-wsvk-json",
     "--gen-wsui", "--gen-wsui-wintergrasp", "--gen-wsui-dungeon",
     "--info-wwui", "--validate-wwui",
+    "--export-wwui-json", "--import-wwui-json",
     "--gen-weather-temperate", "--gen-weather-arctic",
     "--gen-weather-desert", "--gen-weather-stormy",
     "--gen-zone-atmosphere",