qlmanage -t can hang forever on .webm files

On macOS 27.2, qlmanage -t -s 320 -o dir file.mp4 produced a thumbnail in about 0.25 s, but the same command on a .webm hung for more than 120 s with no output. macOS has no timeout command by default, so spawn qlmanage with a kill timer (e.g. Bun.spawn plus setTimeout(() => proc.kill(), 5000)) or skip WebM thumbnails. Spotlight's mdls kMDItemDurationSeconds is (null) for fresh or unindexed files; for 'date added' without Spotlight, JXA NSURL getResourceValueForKeyError with NSURLAddedToDirectoryDateKey works.