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

Closes the JSON round-trip gap on the item-suffix catalog
format shipped this batch. --export-wsuf-json emits all 5
scalar fields plus a dual int + name form for suffixCategory
and a nested stats[] array — only populated stat slots are
emitted to keep hand-edits compact. --import-wsuf-json
clears the trailing stat slots before parsing (so a 2-stat
sidecar correctly leaves slots 2-4 zero) and accepts
suffixCategory by either int or name. Verified byte-
identical round-trip on all three preset emitters (starter
2-stat / magical 1-stat / PvP 3-stat). 863 documented CLI
flags.

tools/editor/cli_arg_required.cpp

@@ -196,6 +196,7 @@ const char* const kArgRequired[] = {
     "--export-wlds-json", "--import-wlds-json",
     "--gen-suf", "--gen-suf-magical", "--gen-suf-pvp",
     "--info-wsuf", "--validate-wsuf",
+    "--export-wsuf-json", "--import-wsuf-json",
     "--gen-weather-temperate", "--gen-weather-arctic",
     "--gen-weather-desert", "--gen-weather-stormy",
     "--gen-zone-atmosphere",