Improve movement, crouching, and add M2 animation

Movement:
- Fix speed controls: Shift=sprint (28), normal run (14), Ctrl=walk (5)
- Reduce character height for doorway clearance (eye height 1.2)
- Add working crouch (C or X key) with smooth transition (eye height 0.6)
- Jump to stand up from crouch

M2 Animation:
- Add animation time tracking per M2 instance
- Add procedural swaying animation in vertex shader
- Update animation each frame for vegetation movement

include/rendering/m2_renderer.hpp

@@ -57,6 +57,11 @@ struct M2Instance {
     float scale;
     glm::mat4 modelMatrix;
 
+    // Animation state
+    float animTime = 0.0f;       // Current animation time
+    float animSpeed = 1.0f;      // Animation playback speed
+    uint32_t animId = 0;         // Current animation sequence
+
     void updateModelMatrix();
 };
 
@@ -100,6 +105,12 @@ public:
     uint32_t createInstanceWithMatrix(uint32_t modelId, const glm::mat4& modelMatrix,
                                        const glm::vec3& position);
 
+    /**
+     * Update animation state for all instances
+     * @param deltaTime Time since last frame
+     */
+    void update(float deltaTime);
+
     /**
      * Render all visible instances
      */