Zig 0.16 module graph (build.zig DAG with per-module addTest, run/smoke
steps), Juicy Main entry, truecolor tty-gated banner, --version/--help.
Wire-exact extern eth/ip/tcp headers with comptime @sizeOf asserts and
an RFC 1071 checksum proven by the canonical 0xb861 IPv4 KAT. AF_PACKET
raw socket that hand-builds and sends one SYN, checking errno not fd<0.
4/4 tests green under Debug and ReleaseSafe.
CarterPerez-dev