fix(editor): NPC ghost preview, scale control, frame sync for M2 rendering

- Ghost preview now shows in NPC mode (follows cursor with creature model)
- Added scale field to CreatureSpawn (default 1.0, slider 0.5-10x)
- NPC instances render at their configured scale
- Scale included in JSON save format
- M2Renderer::update() now runs AFTER beginFrame() so getCurrentFrame()
  returns the correct frame index — fixes instance SSBO mismatch that
  caused draws=0 despite loaded models

tools/editor/npc_spawner.hpp

@@ -39,6 +39,9 @@ struct CreatureSpawn {
     uint32_t armor = 0;
     uint32_t faction = 0; // 0 = neutral
 
+    // Display
+    float scale = 1.0f;
+
     // Behavior
     CreatureBehavior behavior = CreatureBehavior::Stationary;
     float wanderRadius = 10.0f;