CVE-2026-69203: Http4s Ember HTTP/2 does not enforce SETTINGS_MAX_CONCURRENT_STREAMS

An ember server with HTTP/2 enabled (`.withHttp2`) does not enforce `SETTINGS_MAX_CONCURRENT_STREAMS` on streams opened by the peer. A single unauthenticated connection can open an unbounded number of concurrent streams, each of which allocates per-stream server state that is never released, exhausting the heap. ## Impact Unauthenticated remote denial of service (memory exhaustion) against any Ember server built `.withHttp2`. This is the resource-exhaustion class of the HTTP/2 "Rapid Reset" family (CVE-2023-44487). The same unchecked allocation path is reachable on the client via server-initiated `PUSH_PROMISE` frames, so a malicious or compromised server can exhaust an ember-client's heap the same way. ## Preconditions - Server: with `.withHttp2` enabled. - Client: makes HTTP/2 requests to malicious or compromised sites. `enablePush` is not enforced. ## Workarounds - Disable HTTP/2 on `EmberServerBuilder` or `EmberClientBuilder` (default) - Client only: avoid HTTP/2 to untrusted servers until patched.