Fix Create methods: respect user-provided IDs and set timestamps

All service-layer Create methods (team, owner, target, issuer,
certificate) were unconditionally overwriting user-provided IDs with
auto-generated ones and leaving CreatedAt/UpdatedAt as zero values.

This caused three user-visible bugs:
- POST /api/v1/teams with {"id": "t-demo"} returned a generated ID
  like "team-1773601137949154216" instead of "t-demo"
- POST /api/v1/owners referencing the user-provided team_id failed
  with Internal Server Error (FK constraint on non-existent generated ID)
- created_at/updated_at came back as "0001-01-01T00:00:00Z"

Fix: all 9 affected Create methods (both context-aware and handler
interface variants) now check if ID is empty before generating, and
set timestamps to time.Now() if zero-valued. Follows the existing
correct pattern in policy.go CreateRule/CreatePolicy.

Also removes two stale temp files (audit.go.* and issuer.go.*) that
were accidentally committed to the repo.

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

internal/service/certificate.go

@@ -3,6 +3,7 @@ package service
 import (
 	"context"
 	"fmt"
+	"time"
 
 	"github.com/shankar0123/certctl/internal/domain"
 	"github.com/shankar0123/certctl/internal/repository"
@@ -254,7 +255,16 @@ func (s *CertificateService) GetCertificate(id string) (*domain.ManagedCertifica
 
 // CreateCertificate creates a new certificate (handler interface method).
 func (s *CertificateService) CreateCertificate(cert domain.ManagedCertificate) (*domain.ManagedCertificate, error) {
-	cert.ID = generateID("cert")
+	if cert.ID == "" {
+		cert.ID = generateID("cert")
+	}
+	now := time.Now()
+	if cert.CreatedAt.IsZero() {
+		cert.CreatedAt = now
+	}
+	if cert.UpdatedAt.IsZero() {
+		cert.UpdatedAt = now
+	}
 	if err := s.certRepo.Create(context.Background(), &cert); err != nil {
 		return nil, fmt.Errorf("failed to create certificate: %w", err)
 	}