Fix WMO ramp/stair clipping with WoW-style floor snap and collision fixes

Remove active group fast path from getFloorHeight to fix bridge clipping.
Replace ground smoothing with immediate step-up snap (WoW-style: snap up,
smooth down). Accept upward Z from wall collision at all call sites. Skip
floor-like surfaces (absNz >= 0.45) in wall collision to prevent false
wall hits on ramps. Increase getFloorHeight allowAbove from 0.5 to 2.0
for ramp reacquisition. Prefer highest reachable surface in floor selection.

include/rendering/camera_controller.hpp

@@ -161,6 +161,11 @@ private:
     int insideWMOCheckCounter = 0;
     glm::vec3 lastInsideWMOCheckPos = glm::vec3(0.0f);
 
+    // Cached camera WMO floor query (skip if camera moved < 0.3 units)
+    glm::vec3 lastCamFloorQueryPos = glm::vec3(0.0f);
+    std::optional<float> cachedCamWmoFloor;
+    bool hasCachedCamFloor = false;
+
     // Swimming
     bool swimming = false;
     bool wasSwimming = false;