Miscellaneous fixes (#24790)

* stagger the daily region grid rebuild across cameras

Every camera requested its region grid at exactly 02:00, so the requests queued up in the dispatcher and held up recording segment inserts behind them. Each camera now picks a random offset of up to an hour.

* only log ffmpeg crashes when restarting

* round preview skeleton corners to match the player

web/src/components/player/PreviewPlayer.tsx

@@ -332,7 +332,9 @@ function PreviewVideoPlayer({
           {t("noPreviewFoundFor", { cameraName: cameraName })}
         </div>
       )}
-      {firstLoad && <Skeleton className="absolute aspect-video size-full" />}
+      {firstLoad && (
+        <Skeleton className="absolute aspect-video size-full rounded-lg md:rounded-2xl" />
+      )}
     </div>
   );
 }
@@ -555,7 +557,9 @@ function PreviewFramesPlayer({
           {t("noPreviewFoundFor", { cameraName: cameraName })}
         </div>
       )}
-      {firstLoad && <Skeleton className="absolute aspect-video size-full" />}
+      {firstLoad && (
+        <Skeleton className="absolute aspect-video size-full rounded-lg md:rounded-2xl" />
+      )}
     </div>
   );
 }