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/transform_gizmo.hpp

@@ -0,0 +1,77 @@
+#pragma once
+
+#include "rendering/camera.hpp"
+#include <glm/glm.hpp>
+#include <vulkan/vulkan.h>
+#include <vk_mem_alloc.h>
+
+namespace wowee {
+namespace rendering { class VkContext; }
+
+namespace editor {
+
+enum class TransformMode { None, Move, Rotate, Scale };
+enum class TransformAxis { All, X, Y, Z };
+
+class TransformGizmo {
+public:
+    TransformGizmo();
+    ~TransformGizmo();
+
+    bool initialize(rendering::VkContext* ctx, VkRenderPass renderPass,
+                    VkDescriptorSetLayout perFrameLayout);
+    void shutdown();
+
+    void setTarget(const glm::vec3& position, float scale = 1.0f);
+    void setMode(TransformMode mode) { mode_ = mode; }
+    TransformMode getMode() const { return mode_; }
+    void setAxis(TransformAxis axis) { axis_ = axis; }
+    TransformAxis getAxis() const { return axis_; }
+    bool isActive() const { return mode_ != TransformMode::None; }
+
+    // Begin/end drag
+    void beginDrag(const glm::vec2& screenPos);
+    void updateDrag(const glm::vec2& screenPos, const rendering::Camera& camera,
+                    float screenW, float screenH);
+    void endDrag();
+    bool isDragging() const { return dragging_; }
+
+    // Get accumulated transform delta since beginDrag
+    glm::vec3 getMoveDelta() const { return moveDelta_; }
+    glm::vec3 getRotateDelta() const { return rotateDelta_; }
+    float getScaleDelta() const { return scaleDelta_; }
+
+    void render(VkCommandBuffer cmd, VkDescriptorSet perFrameSet);
+
+private:
+    bool createPipeline();
+    void updateBuffers();
+
+    rendering::VkContext* vkCtx_ = nullptr;
+    VkRenderPass renderPass_ = VK_NULL_HANDLE;
+    VkDescriptorSetLayout perFrameLayout_ = VK_NULL_HANDLE;
+
+    VkPipeline pipeline_ = VK_NULL_HANDLE;
+    VkPipelineLayout pipelineLayout_ = VK_NULL_HANDLE;
+    VkBuffer vertexBuffer_ = VK_NULL_HANDLE;
+    VmaAllocation vertexAlloc_ = VK_NULL_HANDLE;
+    uint32_t vertexCount_ = 0;
+
+    TransformMode mode_ = TransformMode::None;
+    TransformAxis axis_ = TransformAxis::All;
+    glm::vec3 targetPos_{0};
+    float targetScale_ = 1.0f;
+    bool visible_ = false;
+
+    bool dragging_ = false;
+    glm::vec2 dragStart_{0};
+    glm::vec2 dragCurrent_{0};
+    glm::vec3 moveDelta_{0};
+    glm::vec3 rotateDelta_{0};
+    float scaleDelta_ = 0.0f;
+
+    struct GizmoVertex { float pos[3]; float color[4]; };
+};
+
+} // namespace editor
+} // namespace wowee