feat(multiplayer): deliver allocated server rosters

server/cmd/game-server-supervisor/main.go

@@ -49,6 +49,7 @@ func main() {
 	imageDigestEnv := options.String("image-digest-env", "COSMIC_CLASH_IMAGE_DIGEST", "environment variable containing this build's sha256 image digest")
 	assignmentReadyAttempts := options.Int("assignment-ready-attempts", 5, "retry attempts for assignment-ready registration after process-ready succeeds (a slow-to-propagate signed roster is not fatal)")
 	assignmentReadyBackoff := options.Duration("assignment-ready-backoff", 2*time.Second, "delay between assignment-ready retry attempts")
+	rosterPath := options.String("roster-path", "", "writable path for the workload-authenticated signed join roster; fetched before the child starts")
 	if err := options.Parse(args[:separator]); err != nil {
 		os.Exit(2)
 	}
@@ -75,6 +76,7 @@ func main() {
 
 		AssignmentReadyAttempts: *assignmentReadyAttempts,
 		AssignmentReadyBackoff:  *assignmentReadyBackoff,
+		RosterPath:              *rosterPath,
 	})
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "game-server-supervisor: %v\n", err)