Add support for passing prompt without -one-shot

Added `-prompt` option
diff --git a/dockerimg/dockerimg.go b/dockerimg/dockerimg.go
index e40a77b..1d6237b 100644
--- a/dockerimg/dockerimg.go
+++ b/dockerimg/dockerimg.go
@@ -77,8 +77,11 @@
 	OutsideOS         string
 	OutsideWorkingDir string
 
-	// If not empty, handle this message and exit
-	OneShot string
+	// If true, exit after the first turn
+	OneShot bool
+
+	// Initial prompt
+	Prompt string
 }
 
 // LaunchContainer creates a docker container for a project, installs sketch and opens a connection to it.
@@ -442,8 +445,11 @@
 	if config.SkabandAddr != "" {
 		cmdArgs = append(cmdArgs, "-skaband-addr="+config.SkabandAddr)
 	}
-	if config.OneShot != "" {
-		cmdArgs = append(cmdArgs, "-one-shot", config.OneShot)
+	if config.Prompt != "" {
+		cmdArgs = append(cmdArgs, "-prompt", config.Prompt)
+	}
+	if config.OneShot {
+		cmdArgs = append(cmdArgs, "-one-shot")
 	}
 	if out, err := combinedOutput(ctx, "docker", cmdArgs...); err != nil {
 		return fmt.Errorf("docker create: %s, %w", out, err)