Improve runtime stutter handling and ground clutter performance

- reduce per-tile ground clutter generation pressure and enforce tighter caps to avoid spikes

- remove expensive detail dedupe scans from the hot render path

- add progressive/lazy clutter updates around player movement to smooth frame pacing

- lower noisy runtime INFO logging to DEBUG/throttled paths

- keep terrain/game screen updates responsive while preserving existing behavior

include/ui/game_screen.hpp

@@ -101,6 +101,7 @@ private:
     bool pendingSeparateBags = true;
     bool pendingAutoLoot = false;
     bool pendingUseOriginalSoundtrack = true;
+    int pendingGroundClutterDensity = 100;
 
     // UI element transparency (0.0 = fully transparent, 1.0 = fully opaque)
     float uiOpacity_ = 0.65f;