dockerimg: pass -x flag to inner sketch to enable experimental features

The -x flag needs to be passed from the outer sketch process to the inner sketch process
to ensure experimental features are correctly enabled across both processes.

Co-Authored-By: sketch <hello@sketch.dev>
diff --git a/cmd/sketch/main.go b/cmd/sketch/main.go
index 7bfb1a6..12e58ea 100644
--- a/cmd/sketch/main.go
+++ b/cmd/sketch/main.go
@@ -270,6 +270,7 @@
 		InitialCommit:     flags.initialCommit,
 		Verbose:           flags.verbose,
 		DockerArgs:        flags.dockerArgs,
+		ExperimentFlag:    flags.experimentFlag.String(),
 	}
 
 	if err := dockerimg.LaunchContainer(ctx, config); err != nil {
diff --git a/dockerimg/dockerimg.go b/dockerimg/dockerimg.go
index 7aecb16..a4c82bc 100644
--- a/dockerimg/dockerimg.go
+++ b/dockerimg/dockerimg.go
@@ -97,6 +97,9 @@
 
 	// DockerArgs are additional arguments to pass to the docker create command
 	DockerArgs string
+
+	// ExperimentFlag contains the experimental features to enable
+	ExperimentFlag string
 }
 
 // LaunchContainer creates a docker container for a project, installs sketch and opens a connection to it.
@@ -468,6 +471,7 @@
 		"-outside-os="+config.OutsideOS,
 		"-outside-working-dir="+config.OutsideWorkingDir,
 		"-open=false",
+		"-x="+config.ExperimentFlag,
 	)
 	if config.Model != "" {
 		cmdArgs = append(cmdArgs, "-model="+config.Model)