Carry raw response header values through fetch, caches, redirects,
renderer delivery, workers, and protocol records. Convert explicitly
at WebIDL and protocol text boundaries while preserving opaque bytes.
Keep legacy CacheStorage and service worker metadata readable, and
advance the HTTP cache format for raw header values.
Validation:
- cargo fmt --all
- cargo clippy --workspace --all-targets --all-features -- -D warnings
- cargo nextest run --no-fail-fast