style: run gofmt -s across all Go files

Fixes Go Report Card gofmt score from 52% to 100%.
Pure formatting changes — no logic modifications.

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

internal/service/certificate_test.go

@@ -18,8 +18,8 @@ func TestCreateCertificate(t *testing.T) {
 		Events: []*domain.AuditEvent{},
 	}
 	policyRepo := &mockPolicyRepo{
-		Rules:       make(map[string]*domain.PolicyRule),
-		Violations:  []*domain.PolicyViolation{},
+		Rules:      make(map[string]*domain.PolicyRule),
+		Violations: []*domain.PolicyViolation{},
 	}
 
 	policyService := NewPolicyService(policyRepo, NewAuditService(auditRepo))