Fix ramp clipping by tightening sweep steps, disable shadows by default

Sweep step size reduced from 1.0f back to 0.65f with max 3 steps (was 2)
to prevent clipping through ramps in Stormwind. All paths updated: follow,
free-fly, and swimming.

Shadows disabled by default in renderer, settings UI, and settings defaults.

include/rendering/renderer.hpp

@@ -192,7 +192,7 @@ private:
     glm::mat4 lightSpaceMatrix = glm::mat4(1.0f);
     glm::vec3 shadowCenter = glm::vec3(0.0f);
     bool shadowCenterInitialized = false;
-    bool shadowsEnabled = true;
+    bool shadowsEnabled = false;
 
 public:
     void setShadowsEnabled(bool enabled) { shadowsEnabled = enabled; }