fix(export): compute requiredEndSec for decode termination handling

Add requiredEndSec calculation to properly handle early decode termination by using the last segment's end time. This addresses issues with export processing on Windows platforms.

src/lib/exporter/streamingDecoder.ts

@@ -253,6 +253,8 @@ export class StreamingVideoDecoder {
 			this.computeSegments(this.metadata.duration, trimRegions),
 			speedRegions,
 		);
+		const requiredEndSec = segments[segments.length - 1]?.endSec ?? 0;
+		
 		const segmentOutputFrameCounts = segments.map((segment) =>
 			Math.ceil(((segment.endSec - segment.startSec) / segment.speed) * targetFrameRate),
 		);