rendering: re-enable WMO camera collision with asymmetric smoothing

Previously disabled because the per-frame raycast caused erratic zoom
snapping at doorway transitions.  Re-enable using an asymmetrically-
smoothed collision limit: pull-in reacts quickly (τ≈60 ms) to prevent
the camera from ever visibly clipping through walls, while recovery is
slow (τ≈400 ms) so walking through a doorway zooms back out gradually
instead of snapping.

Uses wmoRenderer->raycastBoundingBoxes() which already has strict wall
filters (|normal.z|<0.20, surface-alignment check, ±0.9 height band)
to ignore floors, ramps, and arch geometry.

include/rendering/camera_controller.hpp

@@ -156,6 +156,7 @@ private:
     static constexpr float MAX_PITCH = 35.0f;       // Limited upward look
     glm::vec3* followTarget = nullptr;
     glm::vec3 smoothedCamPos = glm::vec3(0.0f);     // For smooth camera movement
+    float smoothedCollisionDist_ = -1.0f;           // Asymmetrically-smoothed WMO collision limit (-1 = uninitialised)
 
     // Gravity / grounding
     float verticalVelocity = 0.0f;