feat(editor): add WTLE JSON round-trip (--export/--import-wtle-json)

Closes the editing loop on the talent-tab catalog: dump a .wtle
to JSON, hand-edit roleHint / classMask / displayOrder /
iconPath / backgroundFile (e.g. swap a Mage Frost tab from DPS
to Hybrid, point Holy Paladin's tab to a custom background art
file, reorder displayOrder to put Protection first), re-import
to a byte-identical binary.

The exporter emits both roleHint (int 0..4) and the human-
readable roleHintName ("dps" / "tank" / "healer" / "hybrid" /
"pet"); the importer accepts either form.

Verified byte-identical round-trip on all three presets
(warrior / mage / paladin). CLI flag count 963 -> 965.

tools/editor/cli_arg_required.cpp

@@ -239,6 +239,7 @@ const char* const kArgRequired[] = {
     "--export-wpsp-json", "--import-wpsp-json",
     "--gen-tle", "--gen-tle-mage", "--gen-tle-paladin",
     "--info-wtle", "--validate-wtle",
+    "--export-wtle-json", "--import-wtle-json",
     "--gen-weather-temperate", "--gen-weather-arctic",
     "--gen-weather-desert", "--gen-weather-stormy",
     "--gen-zone-atmosphere",