feat: add --format json support to apps:list

The `apps:list` command now accepts a `--format` flag that defaults to `stdout` and can be set to `json` to emit the app names as a JSON array, matching the JSON output the `:report` subcommands already provide. When no apps exist, the JSON output is an empty array.

plugins/apps/src/commands/commands.go

@@ -23,7 +23,7 @@ Additional commands:`
     apps:create <app>, Create a new app
     apps:destroy <app>, Permanently destroy an app
     apps:exists <app>, Checks if an app exists
-    apps:list, List your apps
+    apps:list [--format stdout|json], List your apps
     apps:lock <app>, Locks an app for deployment
     apps:locked <app>, Checks if an app is locked for deployment
     apps:rename <old-app> <new-app>, Rename an app
@@ -43,7 +43,7 @@ func main() {
 		args.Usage = usage
 		args.Parse(os.Args[2:])
 
-		if err := apps.CommandList(); err != nil {
+		if err := apps.CommandList("stdout"); err != nil {
 			common.LogFailWithError(err)
 		}
 	case "apps:help":

plugins/apps/src/subcommands/subcommands.go

@@ -44,8 +44,9 @@ func main() {
 		err = apps.CommandExists(appName)
 	case "list":
 		args := flag.NewFlagSet("apps:list", flag.ExitOnError)
+		format := args.String("format", "stdout", "format: [ stdout | json ]")
 		args.Parse(os.Args[2:])
-		err = apps.CommandList()
+		err = apps.CommandList(*format)
 	case "lock":
 		args := flag.NewFlagSet("apps:lock", flag.ExitOnError)
 		args.Parse(os.Args[2:])