Add mount dust particle effects

Implemented dust cloud particles that spawn at mount feet when running
on the ground, similar to the original WoW. Features:

- Brownish/tan dust particles using point sprite rendering
- Spawn rate proportional to movement speed
- Particles rise up, drift backward, and fade out naturally
- Only active when mounted, moving, and on ground (not flying)
- Smooth particle animation with size growth and alpha fade

Uses similar particle system architecture as swim effects with
GL_POINTS rendering and custom shaders for soft circular particles.

include/rendering/mount_dust.hpp

@@ -0,0 +1,50 @@
+#pragma once
+
+#include <GL/glew.h>
+#include <glm/glm.hpp>
+#include <memory>
+#include <vector>
+
+namespace wowee {
+namespace rendering {
+
+class Camera;
+class Shader;
+
+class MountDust {
+public:
+    MountDust();
+    ~MountDust();
+
+    bool initialize();
+    void shutdown();
+
+    // Spawn dust particles at mount feet when moving on ground
+    void spawnDust(const glm::vec3& position, const glm::vec3& velocity, bool isMoving);
+
+    void update(float deltaTime);
+    void render(const Camera& camera);
+
+private:
+    struct Particle {
+        glm::vec3 position;
+        glm::vec3 velocity;
+        float lifetime;
+        float maxLifetime;
+        float size;
+        float alpha;
+    };
+
+    static constexpr int MAX_DUST_PARTICLES = 300;
+    std::vector<Particle> particles;
+
+    GLuint vao = 0;
+    GLuint vbo = 0;
+    std::unique_ptr<Shader> shader;
+    std::vector<float> vertexData;
+
+    float spawnAccum = 0.0f;
+};
+
+} // namespace rendering
+} // namespace wowee

include/rendering/renderer.hpp

@@ -27,6 +27,7 @@ class Clouds;
 class LensFlare;
 class Weather;
 class SwimEffects;
+class MountDust;
 class CharacterRenderer;
 class WMORenderer;
 class M2Renderer;
@@ -165,6 +166,7 @@ private:
     std::unique_ptr<LensFlare> lensFlare;
     std::unique_ptr<Weather> weather;
     std::unique_ptr<SwimEffects> swimEffects;
+    std::unique_ptr<MountDust> mountDust;
     std::unique_ptr<CharacterRenderer> characterRenderer;
     std::unique_ptr<WMORenderer> wmoRenderer;
     std::unique_ptr<M2Renderer> m2Renderer;