Caddy v2.11.7 Fixes Streaming Regressions

This is a high-priority patch for anyone running Caddy as a reverse proxy, especially workloads that depend on long-lived or intermittent streams.

• –HTTP/2 reverse proxies no longer risk nil-pointer crashes while reading request bodies.
• –SSE streams and POST-based streaming responses avoid the erroneous 60-second cutoff.
• –`Incremental: ?1` provides a standards-based alternative to NGINX’s proprietary `X-Accel-Buffering`, with explicit 501 responses when buffering prevents forwarding. [Caddy documentation](https://caddyserver.com/docs/caddyfile/directives/reverse_proxy)
• –Faster TLS handshakes, cleaner Unix-socket reloads, and correct multiple `Set-Cookie` handling make this broader than a single-bug hotfix.
• –Operators on 2.11.6 should upgrade before tuning around the regressions.