feat(editor): add WIQR JSON round-trip (--export/--import-wiqr-json)

Closes the editing loop on the item-quality catalog: dump a
.wiqr to JSON, hand-edit color hex / vendor multiplier / level
gates / disenchant flag / border texture path (e.g. retune Epic
purple from #a335ee to #c33fff for a brighter look, raise
Heirloom unlock from lvl 80 to 85, mark Legendary as
disenchantable, swap a server-custom tier's border texture),
re-import to a byte-identical binary.

The colors export as raw RGBA uint32 — direct pasting of
0xAARRGGBB hex values without conversion. canBeDisenchanted
round-trips as a JSON bool but accepts int as well so machine-
generated sidecars work too.

Verified byte-identical round-trip on all three presets
(std / srv / raid). CLI flag count 1008 -> 1010.

tools/editor/cli_arg_required.cpp

@@ -259,6 +259,7 @@ const char* const kArgRequired[] = {
     "--export-waur-json", "--import-waur-json",
     "--gen-iqr", "--gen-iqr-server", "--gen-iqr-raid",
     "--info-wiqr", "--validate-wiqr",
+    "--export-wiqr-json", "--import-wiqr-json",
     "--gen-weather-temperate", "--gen-weather-arctic",
     "--gen-weather-desert", "--gen-weather-stormy",
     "--gen-zone-atmosphere",