✨ Enhance NATS configuration and error handling. Introduce stream limits and consumer rules in configuration files. Refactor message processing to handle permanent errors. Update README and development configuration to reflect changes. Add tests for new error handling mechanisms.

internal/app/errors_test.go

@@ -0,0 +1,33 @@
+package app
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestPermanentWrapsError(t *testing.T) {
+	base := errors.New("boom")
+	perr := Permanent(base)
+
+	if perr == nil {
+		t.Fatalf("expected wrapped error, got nil")
+	}
+	if !IsPermanent(perr) {
+		t.Fatalf("expected IsPermanent to be true")
+	}
+	if !errors.Is(perr, base) {
+		t.Fatalf("expected wrapped error to unwrap to base")
+	}
+	if errors.Is(base, perr) {
+		t.Fatalf("expected base not to consider wrapper as same")
+	}
+}
+
+func TestPermanentNil(t *testing.T) {
+	if Permanent(nil) != nil {
+		t.Fatalf("Permanent(nil) should return nil")
+	}
+	if IsPermanent(nil) {
+		t.Fatalf("IsPermanent(nil) should be false")
+	}
+}