Fix double zoom bug in Big Picture Mode display scaling

Removed unconditional CSS zoom call that was causing zoom to be applied
twice (Electron zoom + CSS zoom), resulting in squared scaling values.
Now correctly uses Electron zoom as primary with CSS as fallback only.

renderer/bigpicture.js

@@ -196,7 +196,6 @@ function applyDisplayScale(scalePercent, reason = 'unknown') {
     } else {
       applyCssZoom(zoomFactor);
     }
-    applyCssZoom(zoomFactor);
     console.log(`[BigPicture] Applied display scale ${clampedPercent}% (zoom=${zoomFactor}) via ${reason}`);
   } catch (err) {
     console.warn('[BigPicture] Failed applying display scale:', err);