Improve floor detection for multi-story buildings

- Increase footprint sampling radius from 0.28 to 0.4 units
- Only update floor cache if found floor is close to query height
- Prevents caching wrong floor from different stories

src/rendering/camera_controller.cpp

@@ -518,9 +518,9 @@ void CameraController::update(float deltaTime) {
                 return base;
             };
 
-            // Sample center + small footprint to avoid slipping through narrow floor pieces.
+            // Sample center + footprint to avoid slipping through narrow floor pieces.
             std::optional<float> groundH;
-            constexpr float FOOTPRINT = 0.28f;
+            constexpr float FOOTPRINT = 0.4f;  // Larger footprint for better floor detection
             const glm::vec2 offsets[] = {
                 {0.0f, 0.0f},
                 {FOOTPRINT, 0.0f}, {-FOOTPRINT, 0.0f},
@@ -824,7 +824,7 @@ void CameraController::update(float deltaTime) {
             };
 
             std::optional<float> groundH;
-            constexpr float FOOTPRINT = 0.28f;
+            constexpr float FOOTPRINT = 0.4f;  // Larger footprint for better floor detection
             const glm::vec2 offsets[] = {
                 {0.0f, 0.0f}, {FOOTPRINT, 0.0f}, {-FOOTPRINT, 0.0f}, {0.0f, FOOTPRINT}, {0.0f, -FOOTPRINT}
             };

src/rendering/wmo_renderer.cpp

@@ -1495,8 +1495,10 @@ std::optional<float> WMORenderer::getFloorHeight(float glX, float glY, float glZ
         }
     }
 
-    // Cache the result in persistent grid (never expires)
-    if (bestFloor) {
+    // Cache the result in persistent grid.
+    // Only update cache if we found a floor that's close to query height,
+    // to avoid caching wrong floors when player is on different stories.
+    if (bestFloor && *bestFloor >= glZ - 6.0f) {
         precomputedFloorGrid[gridKey] = *bestFloor;
     }