feat(editor): project system for multi-zone custom expansions

- EditorProject: manages multiple zones in a single project file
  (wowee-project-1.0 JSON format)
- Project stores: name, author, description, version, zone list
- Each zone has: mapName, tileX/Y, biome, description
- Save/load project files (.json) with full round-trip
- Foundation for creating custom expansions with multiple maps,
  quest chains spanning zones, and campaign progression
- getZoneOutputDir() resolves per-zone output paths

tools/editor/editor_project.hpp

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <string>
+#include <vector>
+#include <cstdint>
+
+namespace wowee {
+namespace editor {
+
+struct ProjectZone {
+    std::string mapName;
+    int tileX = 32, tileY = 32;
+    std::string biome;
+    std::string description;
+};
+
+struct EditorProject {
+    std::string name = "Untitled";
+    std::string author;
+    std::string description;
+    std::string version = "1.0";
+    std::string projectDir;
+    uint32_t startMapId = 9000;
+    std::vector<ProjectZone> zones;
+
+    bool save(const std::string& path) const;
+    bool load(const std::string& path);
+    std::string getZoneOutputDir(int zoneIdx) const;
+};
+
+} // namespace editor
+} // namespace wowee