Suppress movement after teleport/portal, add shadow distance slider

- Add movementSuppressTimer to camera controller that forces all movement
  keys to read as false, preventing held W key from carrying through
  loading screens (fixes always-running-forward after instance portals)
- Increase shadow frustum default from 60 to 72 units (+20%)
- Make shadow distance configurable via setShadowDistance() (40-200 range)
- Add shadow distance slider in Video settings tab (persisted to config)

include/rendering/renderer.hpp

@@ -244,6 +244,7 @@ private:
     glm::vec3 shadowCenter = glm::vec3(0.0f);
     bool shadowCenterInitialized = false;
     bool shadowsEnabled = true;
+    float shadowDistance_ = 72.0f;  // Shadow frustum half-extent (default: 72 units)
     uint32_t shadowFrameCounter_ = 0;
 
 
@@ -254,6 +255,8 @@ public:
 
     void setShadowsEnabled(bool enabled) { shadowsEnabled = enabled; }
     bool areShadowsEnabled() const { return shadowsEnabled; }
+    void setShadowDistance(float dist) { shadowDistance_ = glm::clamp(dist, 40.0f, 200.0f); }
+    float getShadowDistance() const { return shadowDistance_; }
     void setMsaaSamples(VkSampleCountFlagBits samples);
 
     void setWaterRefractionEnabled(bool enabled);