feat(editor): BLP→PNG texture export for open format zones

- TextureExporter: converts Blizzard BLP textures to standard PNG
  for fully open redistribution of custom zones
- collectUsedTextures(): finds all texture paths referenced by terrain
- exportTexturesAsPng(): loads BLP via asset manager, writes RGBA PNG
  using stb_image_write to output/MapName/textures/
- Zone export now automatically converts all used textures to PNG
- Client's PNG override system already loads these automatically
  (checks for .png alongside .blp before loading)

Format replacement progress:
- DONE: ADT→WOT/WHM (terrain)
- DONE: WDT→zone.json (map definition)
- DONE: BLP→PNG (textures — auto-exported on zone save)
- TODO: DBC→JSON, M2→open model, WMO→open building

CMakeLists.txt

@@ -1299,6 +1299,7 @@ add_executable(wowee_editor
     tools/editor/content_pack.cpp
     tools/editor/wowee_terrain.cpp
     tools/editor/editor_project.cpp
+    tools/editor/texture_exporter.cpp
     tools/editor/asset_browser.cpp
     tools/editor/editor_water.cpp
     tools/editor/editor_markers.cpp

tools/editor/editor_app.cpp

@@ -3,6 +3,7 @@
 #include "zone_manifest.hpp"
 #include "content_pack.hpp"
 #include "wowee_terrain.hpp"
+#include "texture_exporter.hpp"
 #include "core/coordinates.hpp"
 #include "rendering/vk_context.hpp"
 #include "pipeline/adt_loader.hpp"
@@ -731,6 +732,14 @@ void EditorApp::exportZone(const std::string& outputDir) {
         objectPlacer_.saveToFile(objPath);
     }
 
+    // Export used textures as PNG (open format replacement for BLP)
+    auto usedTextures = TextureExporter::collectUsedTextures(terrain_);
+    if (!usedTextures.empty()) {
+        int exported = TextureExporter::exportTexturesAsPng(
+            assetManager_.get(), usedTextures, base + "/textures");
+        LOG_INFO("Exported ", exported, " textures as PNG");
+    }
+
     // Export open terrain format alongside ADT
     std::string openBase = base + "/" + loadedMap_ + "_" +
                            std::to_string(loadedTileX_) + "_" + std::to_string(loadedTileY_);

tools/editor/texture_exporter.cpp

@@ -0,0 +1,64 @@
+#include "texture_exporter.hpp"
+#include "pipeline/asset_manager.hpp"
+#include "pipeline/blp_loader.hpp"
+#include "core/logger.hpp"
+#include <filesystem>
+#include <algorithm>
+
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#include "stb_image_write.h"
+
+namespace wowee {
+namespace editor {
+
+std::vector<std::string> TextureExporter::collectUsedTextures(const pipeline::ADTTerrain& terrain) {
+    std::unordered_set<std::string> unique;
+    for (const auto& tex : terrain.textures)
+        unique.insert(tex);
+    std::vector<std::string> result(unique.begin(), unique.end());
+    std::sort(result.begin(), result.end());
+    return result;
+}
+
+int TextureExporter::exportTexturesAsPng(pipeline::AssetManager* am,
+                                          const std::vector<std::string>& texturePaths,
+                                          const std::string& outputDir) {
+    namespace fs = std::filesystem;
+    int exported = 0;
+
+    for (const auto& texPath : texturePaths) {
+        auto blpImage = am->loadTexture(texPath);
+        if (!blpImage.isValid()) {
+            LOG_WARNING("Texture not found or invalid: ", texPath);
+            continue;
+        }
+
+        // Build output path: replace backslashes, change .blp to .png
+        std::string outPath = texPath;
+        std::replace(outPath.begin(), outPath.end(), '\\', '/');
+        // Lowercase
+        std::transform(outPath.begin(), outPath.end(), outPath.begin(),
+                       [](unsigned char c) { return std::tolower(c); });
+        // Change extension
+        auto dotPos = outPath.rfind('.');
+        if (dotPos != std::string::npos)
+            outPath = outPath.substr(0, dotPos) + ".png";
+
+        std::string fullPath = outputDir + "/" + outPath;
+        fs::create_directories(fs::path(fullPath).parent_path());
+
+        // Write RGBA data as PNG
+        if (stbi_write_png(fullPath.c_str(), blpImage.width, blpImage.height, 4,
+                           blpImage.data.data(), blpImage.width * 4)) {
+            exported++;
+        } else {
+            LOG_WARNING("Failed to write PNG: ", fullPath);
+        }
+    }
+
+    LOG_INFO("Exported ", exported, "/", texturePaths.size(), " textures as PNG to ", outputDir);
+    return exported;
+}
+
+} // namespace editor
+} // namespace wowee

tools/editor/texture_exporter.hpp

@@ -0,0 +1,26 @@
+#pragma once
+
+#include "pipeline/adt_loader.hpp"
+#include <string>
+#include <vector>
+#include <unordered_set>
+
+namespace wowee {
+namespace pipeline { class AssetManager; }
+
+namespace editor {
+
+class TextureExporter {
+public:
+    // Collect all texture paths referenced by the terrain
+    static std::vector<std::string> collectUsedTextures(const pipeline::ADTTerrain& terrain);
+
+    // Export all used textures as PNG to an output directory
+    // Returns count of successfully exported textures
+    static int exportTexturesAsPng(pipeline::AssetManager* am,
+                                    const std::vector<std::string>& texturePaths,
+                                    const std::string& outputDir);
+};
+
+} // namespace editor
+} // namespace wowee