The container failed to start with 'exec ./webhooker: no such file or
directory'. Two issues:
1. Relative paths: COPY destination and CMD used relative paths (./webhooker).
Changed to absolute paths (/app/webhooker) throughout.
2. Dynamic linking: The binary was built with CGO on Debian (glibc) but
deployed to Alpine (musl). The kernel couldn't find the glibc dynamic
linker, producing the misleading 'no such file or directory' error.
Added a static rebuild step after make check so the binary runs on
Alpine without glibc.