feat(editor): add WSCS JSON round-trip (--export/--import-wscs-json)

Closes the editing loop on the skill-cost catalog: dump a .wscs
to JSON, hand-edit costKind / skill ranges / requiredLevel /
copperCost (e.g. retune Apprentice profession from 1s to 5s for
a faster server, raise Cold Weather Flying from lvl 77 to 75,
add a custom WeaponSkill tier above Master), re-import to a
byte-identical binary.

The exporter emits both costKind (int 0..4) and the human-
readable costKindName ("profession" / "weapon" / "riding" /
"class-skill" / "misc"); the importer accepts either form.

Verified byte-identical round-trip on all three presets
(prof / weapon / riding). CLI flag count 1015 -> 1017.

tools/editor/cli_arg_required.cpp

@@ -262,6 +262,7 @@ const char* const kArgRequired[] = {
     "--export-wiqr-json", "--import-wiqr-json",
     "--gen-scs", "--gen-scs-weapon", "--gen-scs-riding",
     "--info-wscs", "--validate-wscs",
+    "--export-wscs-json", "--import-wscs-json",
     "--gen-weather-temperate", "--gen-weather-arctic",
     "--gen-weather-desert", "--gen-weather-stormy",
     "--gen-zone-atmosphere",