docs(cli): document --non-interactive auto-JSON side effect in help text

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: salmonumbrella

internal/cmd/root.go

@@ -38,7 +38,7 @@ type RootFlags struct {
 	Select         string `name:"select" aliases:"pick,project" help:"In JSON mode, select comma-separated fields (best-effort; supports dot paths). Desire path: use --fields for most commands."`
 	DryRun         bool   `help:"Do not make changes; print intended actions and exit successfully" aliases:"noop,preview,dryrun" short:"n"`
 	Force          bool   `help:"Skip confirmations for destructive commands" aliases:"yes,assume-yes" short:"y"`
-	NoInput        bool   `help:"Never prompt; fail instead (useful for CI)" aliases:"non-interactive,noninteractive"`
+	NoInput        bool   `help:"Never prompt; fail instead (useful for CI). Also defaults to JSON when stdout is non-TTY; use --plain to override." aliases:"non-interactive,noninteractive"`
 	Verbose        bool   `help:"Enable verbose logging" short:"v"`
 }