Play Framework

feat: add HTTP/2 (ALPN h2) inbound support (release 1.12.8)

PF-58 — opt-in via play.http2.enabled. ALPN advertises h2 first with
http/1.1 fallback; PlayHandler stays HTTP/1.1-shaped via per-stream
Http2StreamFrameToHttpObjectCodec so routing and dispatch are unchanged.
Works with both PEM cert+key and JKS keystore. Disabled by default.

Also adds netty-transport-native-unix-common-4.2.12.Final to fix a
pre-existing latent bug: SslHandler.handlerAdded references
io.netty.channel.unix.UnixChannel unconditionally, which made every
HTTPS connection fail at runtime since the Netty 4.2 migration. Surfaced
when PF-58 added the first integration test that opens a real TLS socket.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>