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_viewport.hpp

@@ -0,0 +1,96 @@
+#pragma once
+
+#include "rendering/vk_frame_data.hpp"
+#include "rendering/terrain_renderer.hpp"
+#include "rendering/m2_renderer.hpp"
+#include "rendering/wmo_renderer.hpp"
+#include "rendering/camera.hpp"
+#include "editor_water.hpp"
+#include "editor_markers.hpp"
+#include "transform_gizmo.hpp"
+#include "object_placer.hpp"
+#include "npc_spawner.hpp"
+#include <vulkan/vulkan.h>
+#include <vk_mem_alloc.h>
+#include <memory>
+
+namespace wowee {
+namespace pipeline { class AssetManager; }
+namespace rendering { class VkContext; class VkTexture; }
+
+namespace editor {
+
+class EditorViewport {
+public:
+    EditorViewport();
+    ~EditorViewport();
+
+    bool initialize(rendering::VkContext* ctx, pipeline::AssetManager* am, rendering::Camera* cam);
+    void shutdown();
+
+    bool loadTerrain(const pipeline::TerrainMesh& mesh,
+                     const std::vector<std::string>& texturePaths,
+                     int tileX, int tileY);
+    void clearTerrain();
+
+    void updateWater(const pipeline::ADTTerrain& terrain, int tileX, int tileY);
+    void updateMarkers(const std::vector<PlacedObject>& objects);
+    void placeM2(const std::string& path, const glm::vec3& pos, const glm::vec3& rot, float scale);
+    void placeWMO(const std::string& path, const glm::vec3& pos, const glm::vec3& rot);
+    void clearObjects();
+    void rebuildObjects(const std::vector<PlacedObject>& objects,
+                        const std::vector<CreatureSpawn>& npcs = {});
+
+    void update(float deltaTime);
+    void render(VkCommandBuffer cmd);
+
+    // Ghost preview for placement
+    void setGhostPreview(const std::string& path, const glm::vec3& pos,
+                         const glm::vec3& rotDeg, float scale);
+    void clearGhostPreview();
+
+    TransformGizmo& getGizmo() { return gizmo_; }
+
+    void setWireframe(bool enabled);
+    bool isWireframe() const { return wireframe_; }
+
+    rendering::TerrainRenderer* getTerrainRenderer() { return terrainRenderer_.get(); }
+
+private:
+    bool createPerFrameResources();
+    void destroyPerFrameResources();
+    void updatePerFrameUBO();
+
+    rendering::VkContext* vkCtx_ = nullptr;
+    pipeline::AssetManager* assetManager_ = nullptr;
+    rendering::Camera* camera_ = nullptr;
+
+    std::unique_ptr<rendering::TerrainRenderer> terrainRenderer_;
+    std::unique_ptr<rendering::M2Renderer> m2Renderer_;
+    std::unique_ptr<rendering::WMORenderer> wmoRenderer_;
+    EditorWater waterRenderer_;
+    EditorMarkers markerRenderer_;
+    TransformGizmo gizmo_;
+
+    static constexpr uint32_t MAX_FRAMES = 2;
+    VkDescriptorSetLayout perFrameSetLayout_ = VK_NULL_HANDLE;
+    VkDescriptorPool sceneDescPool_ = VK_NULL_HANDLE;
+    VkDescriptorSet perFrameDescSets_[MAX_FRAMES] = {};
+    VkBuffer perFrameUBOs_[MAX_FRAMES] = {};
+    VmaAllocation perFrameUBOAllocs_[MAX_FRAMES] = {};
+    void* perFrameUBOMapped_[MAX_FRAMES] = {};
+
+    std::unique_ptr<rendering::VkTexture> dummyShadowTexture_;
+    VkSampler shadowSampler_ = VK_NULL_HANDLE;
+
+    bool wireframe_ = false;
+
+    // Ghost preview state
+    std::string ghostModelPath_;
+    uint32_t ghostModelId_ = 0;
+    uint32_t ghostInstanceId_ = 0;
+    bool ghostActive_ = false;
+};
+
+} // namespace editor
+} // namespace wowee