0d7b985469
handlePresignAudio now checks AudioExists before presigning; previously it would generate a valid-looking signed URL for a non-existent object, causing the browser to get 404 from MinIO directly. - Add AudioExists to Store interface and HybridStore - Guard handlePresignAudio with AudioExists check, return 404 if missing - Propagate 404 through presignAudio() in minio.ts (typed error.status=404) - SvelteKit presign route forwards 404 to the browser instead of 500