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

pkg/readers/reader.go

@@ -32,6 +32,10 @@ type ReaderOptions struct {
 	// fail on an unknown namespace or key instead of preserving them silently.
 	StrictDirectives bool
 
+	// Progress receives human-readable status updates while a reader is working.
+	// It is optional so library users can opt in without coupling readers to a UI.
+	Progress func(string)
+
 	// Additional options can be added here as needed
 	Metadata map[string]interface{}
 }