Turn the 1446-line packet.rs into a packet/ directory module (mod.rs facade
+ header/packetize/reassemble/tests) behind glob re-exports, so every
crate::packet::X path stays byte-stable. Pure move: the header consts +
PacketHeader -> header.rs; Packetizer -> packetize.rs; the Reassembler cluster
(kept WHOLE -- disjoint-borrow hot path) + loss-window consts -> reassemble.rs;
the inline #[cfg(test)] block -> tests.rs. Sole visibility change:
LOSS_WINDOW_NS -> pub(super) (a test imports it). No behavior change.
Verified on both platforms from a clean HEAD snapshot: Linux clippy
(--features quic and --no-default-features, --all-targets -D warnings) + full
cargo test; Windows clippy (both feature sets) + cargo test --lib (156 pass).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
