v0.16.1

Adds gzip response support and a faster large-body send path.

- http-response-gzip / response-compressible? : reusable Content-Encoding: gzip negotiation (Accept-Encoding check, compressible-type filter, size floor, Content-Encoding + Vary headers). Built on the gzip-compress primitive in (sigil archive). Any Sigil HTTP server can opt in with one call; sigil serve now uses it (≈5x smaller payloads on a wasm app). - send-response: use socket-write's new start/end offsets to resend the unsent tail in place rather than copying it each partial write, turning an O(n^2) write loop over a large body on a slow link into O(n).

Additive and backward compatible (patch release).