The "Compute SHA-256 checksums" step used `mapfile -t` (a bash 4+ builtin) but
macOS GitHub runners execute `shell: bash` as /bin/bash 3.2, which has no
`mapfile`. The step exited 127 ("mapfile: command not found") on the macOS leg,
so `SHA256SUMS-macOS Apple Silicon.txt` was never produced/uploaded for v0.3.1
and v0.3.2 (the binaries themselves shipped fine; only the macOS checksum file
was missing and had to be regenerated by hand each time).
Replace `mapfile` with a portable `while IFS= read -r … done < <(find … | sort)`
loop (works on bash 3.2). Verified on bash 3.2.57: builds the array correctly,
handles spaces in bundle filenames. Linux/Windows legs are unaffected.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
