feat(editor): add standalone world editor (rough/WIP)

Standalone wowee_editor tool for creating custom WoW zones.
This is a rough initial implementation — many features work but
M2/WMO rendering still has issues (frame sync, texture layout
transitions) and needs further polish.

Terrain:
- Create new blank terrain with 10 biome types (Grassland, Forest,
  Jungle, Desert, Barrens, Snow, Swamp, Rocky, Beach, Volcanic)
- Load existing ADT tiles from extracted game data
- Sculpt brushes: Raise, Lower, Smooth, Flatten, Level
- Chunk edge stitching prevents seams between tiles
- Undo/redo (100-deep stack, Ctrl+Z/Ctrl+Shift+Z)
- Save to WoW ADT/WDT format

Texture Painting:
- Paint/Erase/Replace Base modes
- Full tileset texture browser (1285 textures from manifest)
- Per-zone directory filtering and search
- Alpha map editing with 4-layer limit (auto-replaces weakest)

Object Placement:
- M2 and WMO model placement with full manifest browser (11k M2s, 2k WMOs)
- M2Renderer + WMORenderer integrated (loads .skin files for WotLK)
- Ghost preview follows cursor before placing
- Ctrl+click selection, right-click context menu
- Transform gizmo (Move/Rotate/Scale with axis constraints)
- Position/rotation/scale editing in properties panel

NPC/Monster System:
- 631 creature presets scanned from manifest, categorized
  (Critters, Beasts, Humanoids, Undead, Demons, etc.)
- Stats editor: level, health, mana, damage, armor, faction
- Behavior: Stationary, Patrol, Wander, Scripted
- Aggro/leash radius, respawn time, flags (hostile/vendor/etc.)
- Save creature spawns to JSON

Water:
- Place water at configurable height per chunk
- Liquid types: Water, Ocean, Magma, Slime
- Rendered as translucent colored quads
- Saved in ADT MH2O format

Infrastructure:
- Free-fly camera (WASD/QE, right-drag look, scroll speed)
- 5-mode toolbar: Sculpt | Paint | Objects | Water | NPCs
- Asset browser indexes full manifest on startup
- Editor water/marker shaders (pos+color vertex format)
- forceNoCull added to M2Renderer for editor use
- AssetManifest::getEntries() and AssetManager::getManifest() exposed

Known issues:
- M2/WMO rendering may not display on first placement (frame index
  sync between update/render was misaligned — now fixed but untested
  end-to-end)
- Validation layer errors on shutdown (resource cleanup ordering)
- Object placement on steep terrain can miss raycast
- No undo for texture painting or object placement yet

tools/editor/editor_app.hpp

@@ -0,0 +1,107 @@
+#pragma once
+
+#include "editor_camera.hpp"
+#include "editor_viewport.hpp"
+#include "editor_ui.hpp"
+#include "terrain_editor.hpp"
+#include "texture_painter.hpp"
+#include "object_placer.hpp"
+#include "npc_spawner.hpp"
+#include "npc_presets.hpp"
+#include "asset_browser.hpp"
+#include "core/window.hpp"
+#include "pipeline/asset_manager.hpp"
+#include <string>
+#include <memory>
+
+namespace wowee {
+namespace editor {
+
+enum class EditorMode { Sculpt, Paint, PlaceObject, Water, NPC };
+
+class EditorApp {
+public:
+    EditorApp();
+    ~EditorApp();
+
+    bool initialize(const std::string& dataPath);
+    void run();
+    void shutdown();
+
+    void loadADT(const std::string& mapName, int tileX, int tileY);
+    void createNewTerrain(const std::string& mapName, int tileX, int tileY, float baseHeight, Biome biome);
+    void saveADT(const std::string& path);
+    void saveWDT(const std::string& path);
+
+    void requestQuit();
+    void resetCamera();
+    void setWireframe(bool enabled);
+    bool isWireframe() const;
+
+    EditorCamera& getEditorCamera() { return camera_; }
+    TerrainEditor& getTerrainEditor() { return terrainEditor_; }
+    TexturePainter& getTexturePainter() { return texturePainter_; }
+    ObjectPlacer& getObjectPlacer() { return objectPlacer_; }
+    NpcSpawner& getNpcSpawner() { return npcSpawner_; }
+    NpcPresets& getNpcPresets() { return npcPresets_; }
+    AssetBrowser& getAssetBrowser() { return assetBrowser_; }
+    rendering::TerrainRenderer* getTerrainRenderer();
+    pipeline::AssetManager* getAssetManager() { return assetManager_.get(); }
+
+    const std::string& getLoadedMap() const { return loadedMap_; }
+    int getLoadedTileX() const { return loadedTileX_; }
+    int getLoadedTileY() const { return loadedTileY_; }
+    bool hasTerrainLoaded() const { return terrain_.isLoaded(); }
+
+    core::Window* getWindow() { return window_.get(); }
+
+    EditorMode getMode() const { return mode_; }
+    void setMode(EditorMode m) { mode_ = m; }
+    void markObjectsDirty() { objectsDirty_ = true; }
+
+    void startGizmoMode(TransformMode mode);
+    void setGizmoAxis(TransformAxis axis);
+    TransformGizmo& getGizmo() { return viewport_.getGizmo(); }
+
+    float getWaterHeight() const { return waterHeight_; }
+    void setWaterHeight(float h) { waterHeight_ = h; }
+    uint16_t getWaterType() const { return waterType_; }
+    void setWaterType(uint16_t t) { waterType_ = t; }
+
+private:
+    void processEvents();
+    void updateTerrainEditing(float dt);
+    void refreshDirtyChunks();
+    void initImGui();
+    void shutdownImGui();
+
+    std::unique_ptr<core::Window> window_;
+    std::unique_ptr<pipeline::AssetManager> assetManager_;
+    EditorCamera camera_;
+    EditorViewport viewport_;
+    EditorUI ui_;
+    TerrainEditor terrainEditor_;
+    TexturePainter texturePainter_;
+    ObjectPlacer objectPlacer_;
+    NpcSpawner npcSpawner_;
+    NpcPresets npcPresets_;
+    AssetBrowser assetBrowser_;
+
+    pipeline::ADTTerrain terrain_;
+
+    bool imguiInitialized_ = false;
+    bool painting_ = false;
+    bool objectsDirty_ = false;
+    size_t lastObjectCount_ = 0;
+    EditorMode mode_ = EditorMode::Sculpt;
+    float waterHeight_ = 100.0f;
+    uint16_t waterType_ = 0;
+    std::string dataPath_;
+
+    std::string loadedMap_;
+    int loadedTileX_ = -1;
+    int loadedTileY_ = -1;
+};
+
+} // namespace editor
+} // namespace wowee