feat(editor): WCRA JSON round-trip closure

Adds --export-wcra-json / --import-wcra-json. Variable-length
reagent arrays serialize as JSON object array of {itemId, count}
allowing hand-edits of recipe formulas. tradeSkillName field on
export is informational (tradeSkillId int is authoritative).
All 3 presets (alchemy/engineering/blacksmithing) byte-identical
binary roundtrip OK including the 5-reagent Target Dummy
recipe.

Live-tested perpetual-motion validator: hand-mutated Minor
Healing Potion (recipeId 1, produces itemId 118) to add itemId
118 to its reagents. Validator correctly errored: "reagent
itemId equals producedItemId=118 — recipe consumes what it
makes (perpetual-motion bug)" — catches a class of crafting
bugs that would silently let players duplicate items.

CLI flag count 1398 -> 1400.

tools/editor/cli_arg_required.cpp

@@ -409,6 +409,7 @@ const char* const kArgRequired[] = {
     "--export-wqgr-json", "--import-wqgr-json",
     "--gen-cra-alchemy", "--gen-cra-engineering", "--gen-cra-blacksmithing",
     "--info-wcra", "--validate-wcra",
+    "--export-wcra-json", "--import-wcra-json",
     "--gen-weather-temperate", "--gen-weather-arctic",
     "--gen-weather-desert", "--gen-weather-stormy",
     "--gen-zone-atmosphere",