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/object_placer.hpp

@@ -0,0 +1,75 @@
+#pragma once
+
+#include "pipeline/adt_loader.hpp"
+#include "rendering/camera.hpp"
+#include <glm/glm.hpp>
+#include <string>
+#include <vector>
+#include <cstdint>
+
+namespace wowee {
+namespace editor {
+
+enum class PlaceableType { M2, WMO };
+
+struct PlacedObject {
+    PlaceableType type;
+    std::string path;
+    uint32_t nameId;
+    uint32_t uniqueId;
+    glm::vec3 position;
+    glm::vec3 rotation; // degrees
+    float scale;        // 1.0 = normal
+    bool selected = false;
+};
+
+class ObjectPlacer {
+public:
+    void setTerrain(pipeline::ADTTerrain* terrain) { terrain_ = terrain; }
+
+    void setActivePath(const std::string& path, PlaceableType type);
+    const std::string& getActivePath() const { return activePath_; }
+    PlaceableType getActiveType() const { return activeType_; }
+
+    // Place object at world position
+    void placeObject(const glm::vec3& position);
+
+    // Select object nearest to ray
+    int selectAt(const rendering::Ray& ray, float maxDist = 50.0f);
+    void clearSelection();
+    int getSelectedIndex() const { return selectedIdx_; }
+    PlacedObject* getSelected();
+
+    // Transform selected
+    void moveSelected(const glm::vec3& delta);
+    void rotateSelected(const glm::vec3& deltaDeg);
+    void scaleSelected(float delta);
+    void deleteSelected();
+
+    // Sync placed objects back to ADTTerrain structs
+    void syncToTerrain();
+
+    const std::vector<PlacedObject>& getObjects() const { return objects_; }
+    size_t objectCount() const { return objects_.size(); }
+
+    float getPlacementRotationY() const { return placementRotY_; }
+    void setPlacementRotationY(float deg) { placementRotY_ = deg; }
+    float getPlacementScale() const { return placementScale_; }
+    void setPlacementScale(float s) { placementScale_ = s; }
+
+private:
+    uint32_t nextUniqueId();
+
+    pipeline::ADTTerrain* terrain_ = nullptr;
+    std::string activePath_;
+    PlaceableType activeType_ = PlaceableType::M2;
+
+    std::vector<PlacedObject> objects_;
+    int selectedIdx_ = -1;
+    uint32_t uniqueIdCounter_ = 1;
+    float placementRotY_ = 0.0f;
+    float placementScale_ = 1.0f;
+};
+
+} // namespace editor
+} // namespace wowee