feat: integrate Wowee Open Terrain loader into client terrain pipeline

The wowee client can now load custom zones exported from the editor
using the novel WOT/WHM format — no Blizzard files needed.

Loading priority in TerrainManager::prepareTile():
1. Check custom_zones/{mapName}/{mapName}_{x}_{y}.wot/.whm
2. Check output/{mapName}/{mapName}_{x}_{y}.wot/.whm (editor output)
3. Fall back to World\Maps\...\*.adt (standard extracted data)

Pipeline:
- WoweeTerrainLoader in src/pipeline/ (shared between client + editor)
- Loads .whm binary heightmap (WHM1 magic, 256 chunks × 145 floats)
- Loads .wot JSON metadata (textures, layers, holes, water)
- Populates the same ADTTerrain struct the mesh generator uses
- obj0 merge only runs for ADT-loaded tiles (custom zones have no obj0)

To use: export zone from editor → files appear in output/ → client
loads them automatically on next terrain request for that map name.

include/pipeline/wowee_terrain_loader.hpp

@@ -0,0 +1,28 @@
+#pragma once
+
+#include "pipeline/adt_loader.hpp"
+#include <string>
+#include <vector>
+
+namespace wowee {
+namespace pipeline {
+
+// Loader for the Wowee Open Terrain format (.wot/.whm)
+// Novel format — no Blizzard structures, fully portable
+class WoweeTerrainLoader {
+public:
+    // Load terrain from .whm binary heightmap file
+    static bool loadHeightmap(const std::string& whmPath, ADTTerrain& terrain);
+
+    // Load terrain metadata from .wot JSON file
+    static bool loadMetadata(const std::string& wotPath, ADTTerrain& terrain);
+
+    // Full load: .wot metadata + .whm heightmap
+    static bool load(const std::string& basePath, ADTTerrain& terrain);
+
+    // Check if a wowee open terrain exists at the given base path
+    static bool exists(const std::string& basePath);
+};
+
+} // namespace pipeline
+} // namespace wowee