Default 'Install dependencies?' prompt to yes in agent create TUI (#885)

The install confirm seeded its cursor from cmd.Bool("install"), which is
false when the flag isn't passed, leaving the prompt defaulted to No. Seed
install=true before the form so the common case (Yes) is preselected.

Author: u9g

cmd/lk/app.go

@@ -430,6 +430,8 @@ func setupTemplate(ctx context.Context, cmd *cli.Command) error {
 	bootstrap.WriteDotEnv(appName, envOutputFile, env, true)
 
 	if !cmd.IsSet("install") && !SkipPrompts(cmd) {
+		// Default the prompt to "yes" — installing deps is the common case.
+		install = true
 		if err := huh.NewForm(huh.NewGroup(util.Confirm().
 			Title("Install dependencies?").
 			Value(&install).