Also frees main's args and the message of a failing main (valgrind was not clean on two tests).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
src/embedded.fch (made by tools/pack.fch, checked by tests/run.sh) holds runtime/finch_rt.c and std/; when they aren't
beside the binary they're written to the cache folder once. All the sh/cmd specifics of the driver (quoting, temp dir,
mkdir, rm, mv, null device, path separator, cache dir, binary stdio) moved into host.fch / host_windows.fch.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015f73FesGZGYPkmDvUcj6QX