fix(gamestream): announce the stream marker + lifecycle events on the compat plane

Only the native punktfunk/1 loop announced the script-facing marker file,
so a Moonlight session left it absent and wrapper scripts took their
"not streaming" branch mid-stream. The GameStream plane now announces
before run() (the marker must exist when the title's wrapper executes)
and retracts before client.disconnected, keeping the native loop's event
order; StreamRef call sites carry the plane/launch fields.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

crates/punktfunk-host/src/native.rs

@@ -1173,6 +1173,7 @@ async fn serve_session(
         hdr: welcome.color.is_hdr(),
         client: hello.name.clone().unwrap_or_default(),
         launch: hello.launch.clone(),
+        plane: crate::events::Plane::Native,
     });
     // The session's launch, threaded into the data plane. Windows carries the store-qualified id
     // (spawned into the interactive user session once capture is live); other hosts resolve the id