feat: complete client integration for all 6 open formats

- Wire WOB buildings into WMO render pipeline (loads→converts→renders)
- Implement JSON DBC loading in DBCFile::loadJSON() with nlohmann/json
- Wire JSON DBC override into AssetManager (custom_zones/output scan)
- Add WMO→WOB conversion with full geometry (fromWMO)
- Replace placeholder WOB export with real WMO→WOB conversion in editor
- Add --convert-wmo CLI flag for batch WMO→WOB conversion
- Store discovered custom zones on Renderer with getCustomZones() accessor
- Add isCustomZone_ member to TerrainManager

All 6 Blizzard format replacements now fully load in the client:
  ADT→WOT/WHM, WDT→zone.json, BLP→PNG, DBC→JSON, M2→WOM, WMO→WOB

include/rendering/renderer.hpp

@@ -14,6 +14,7 @@
 #include "rendering/vk_frame_data.hpp"
 #include "rendering/vk_utils.hpp"
 #include "rendering/sky_system.hpp"
+#include "pipeline/custom_zone_discovery.hpp"
 
 namespace wowee {
 namespace core { class Window; }
@@ -188,6 +189,8 @@ public:
     game::ZoneManager* getZoneManager() { return zoneManager.get(); }
     LightingManager* getLightingManager() { return lightingManager.get(); }
 
+    const std::vector<pipeline::CustomZoneInfo>& getCustomZones() const { return customZones_; }
+
 private:
     void runDeferredWorldInitStep(float deltaTime);
 
@@ -267,6 +270,7 @@ private:
     void renderShadowPass();
     glm::mat4 computeLightSpaceMatrix();
 
+    std::vector<pipeline::CustomZoneInfo> customZones_;
     pipeline::AssetManager* cachedAssetManager = nullptr;
 
     // Spell visual effects — owned SpellVisualSystem (extracted from Renderer §4.4)