Release v1.6.7

Add proactive disk-busy detection: lower STREAM_HIGH_WATER_MARK from 2 MB
to 512 KB so backpressure triggers sooner, and monitor stream.writableLength
to show "Warte auf Festplatte" after 300 ms of undrained writes — before
actual backpressure hits.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/main/constants.ts

@@ -19,7 +19,8 @@ export const CHUNK_SIZE = 512 * 1024;
 export const WRITE_BUFFER_SIZE = 512 * 1024;       // 512 KB write buffer (JDownloader: 500 KB)
 export const WRITE_FLUSH_TIMEOUT_MS = 2000;         // 2s flush timeout
 export const ALLOCATION_UNIT_SIZE = 4096;           // 4 KB NTFS alignment
-export const STREAM_HIGH_WATER_MARK = 2 * 1024 * 1024;  // 2 MB stream buffer (JDownloader: Java NIO FileChannel default ~8 MB)
+export const STREAM_HIGH_WATER_MARK = 512 * 1024;       // 512 KB stream buffer — lower than before (2 MB) so backpressure triggers sooner when disk is slow
+export const DISK_BUSY_THRESHOLD_MS = 300;               // Show "Warte auf Festplatte" if writableLength > 0 for this long
 
 export const SAMPLE_DIR_NAMES = new Set(["sample", "samples"]);
 export const SAMPLE_VIDEO_EXTENSIONS = new Set([".mkv", ".mp4", ".avi", ".mov", ".wmv", ".m4v", ".ts", ".m2ts", ".webm"]);