Break the 1302-line quic/msgs.rs into four flat sibling modules behind the
quic facade's glob re-exports, so every crate::quic::X path stays byte-stable:
handshake.rs (Hello/Welcome/Start + codecs), caps.rs (video-cap bits, codec &
chroma negotiation, ColorInfo), control.rs (typed CTL_MAGIC messages + frame),
pairing.rs (SPAKE2 ceremony messages). msgs.rs is deleted; quic/mod.rs gains the
four `mod`/`pub use` lines and the `pub use crate::reject::*` hoist (moved up from
msgs.rs). Pure move; no wire-format or behavior change. Private helpers
(truncate_to, put_bytes, get_bytes) stay with their sole callers; no visibility
changes.
Verified both platforms from clean HEAD snapshots: Linux clippy (quic +
no-default, -D warnings) + full cargo test (157 lib + integration); Windows
clippy (both) + test --lib (156).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
