Play Framework

test(ws): add WS integration coverage for HTTPS/H2/h2c (PF-107)

Pins the PF-104 acceptance criterion that the OkHttp 5 WS transport
round-trips against a real server over HTTPS (with h2 ALPN) and over
cleartext HTTP without re-introducing the JDK HttpClient h2c-upgrade
hang. Adds a POST /post-json fixture route and an http.port=19080 test
listener; bundles a JKS truststore built at runtime from the existing
self-signed PEM so WSAsync's ssl.cavalidation=false path can be
exercised without leaking trust into the production default.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>