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

Closes the JSON round-trip gap on the creature equipment
catalog format shipped last batch (50th open format). All
fields are scalar — no enum widening — so the JSON mapping
is a direct dump. Slot fields default to the canonical
attachment-table values (mainhand=16, offhand=17,
ranged=18) when omitted from a sidecar, so hand-edits don't
need to spell out the slot numbers for typical loadouts.
Verified byte-identical round-trip on all three preset
emitters (starter / bosses / ranged). 762 documented CLI
flags.

tools/editor/cli_arg_required.cpp

@@ -153,6 +153,7 @@ const char* const kArgRequired[] = {
     "--export-wtsk-json", "--import-wtsk-json",
     "--gen-ceq", "--gen-ceq-bosses", "--gen-ceq-ranged",
     "--info-wceq", "--validate-wceq",
+    "--export-wceq-json", "--import-wceq-json",
     "--gen-weather-temperate", "--gen-weather-arctic",
     "--gen-weather-desert", "--gen-weather-stormy",
     "--gen-zone-atmosphere",