Single Makefile supports native builds (pkg-config) and cross-compilation
(CROSS_COMPILE/PREFIX env vars). Fixes -Wformat-truncation and
-Wstringop-truncation warnings at -O2 by sizing current_file to match
audio_files (256) and replacing strncpy with snprintf.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
