Restore Progressive-only conditions for downloads and timestamps

- Add TranscodingType == Progressive check to downloads folder condition
- Add TranscodingType == Progressive check to timestamp normalization
- Only applies fixes to actual progressive downloads, not all streaming
- Prevents affecting live TV, HLS playback, and other streaming scenarios

MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs

@@ -7504,9 +7504,9 @@ namespace MediaBrowser.Controller.MediaEncoding
             var inputModifier = GetInputModifier(state, encodingOptions, null);
 
             // Add timestamp normalization for progressive downloads
-            // Always normalize timestamps when not copying them - fixes seeking in mpv/iina/infuse
+            // Fixes seeking issues in strict players like mpv, iina, and infuse
             var timestampArgs = string.Empty;
-            if (!state.BaseRequest.CopyTimestamps)
+            if (state.TranscodingType == TranscodingJobType.Progressive && !state.BaseRequest.CopyTimestamps)
             {
                 timestampArgs = " -avoid_negative_ts make_zero -start_at_zero";
             }