feat(main): add silent mode to suppress output messages

* implement --silent flag to control output verbosity
* update error handling to restore stderr after silent mode
* enhance progress reporting in PostgreSQL reader

cmd/relspec/main.go

@@ -6,9 +6,40 @@ import (
 )
 
 func main() {
-	printVersionHeader(os.Args[1:])
-	if err := rootCmd.Execute(); err != nil {
+	args := os.Args[1:]
+	isSilent := hasSilentFlag(args)
+	if !isSilent {
+		printVersionHeader(args)
+	}
+
+	previousStderr := os.Stderr
+	var nullOutput *os.File
+	if isSilent {
+		var err error
+		nullOutput, err = os.OpenFile(os.DevNull, os.O_WRONLY, 0)
+		if err != nil {
+			fmt.Fprintln(previousStderr, err)
+			os.Exit(1)
+		}
+		os.Stderr = nullOutput
+	}
+
+	err := rootCmd.Execute()
+	if nullOutput != nil {
+		os.Stderr = previousStderr
+		nullOutput.Close()
+	}
+	if err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
 	}
 }
+
+func hasSilentFlag(args []string) bool {
+	for _, arg := range args {
+		if arg == "--silent" || arg == "--silent=true" {
+			return true
+		}
+	}
+	return false
+}