feat(render+admin): exports management (all users' rendered videos)

- render-svc: admin-scoped store (ListAllExports / GetExportByIDAny /
  SoftDeleteExportAny) + GET/DELETE/download-url under /v1/admin-exports
  (admin-gated; separate prefix so it routes to render, not identity's /admin)
- gateway: /v1/admin-exports/* → render
- admin /admin/exports: paginated table of every rendered export with thumbnail,
  type/quality, size, duration, dimensions, produce + expiry dates; download
  (presigned URL) and delete

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/render/internal/db/exports_admin.go

@@ -0,0 +1,63 @@
+package db
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/flatrender/render-svc/internal/models"
+	"github.com/google/uuid"
+)
+
+const exportCols = `id, tenant_id, user_id, saved_project_id, project_id, render_job_id,
+	image, path, file_extension, file_type::text, render_quality::text,
+	create_type::text, size_bytes, duration_sec, width, height,
+	produce_date, auto_delete_date, delete_notified, created_at, deleted_at`
+
+// ListAllExports returns every export across users (admin view), paginated.
+func (s *Store) ListAllExports(ctx context.Context, page, pageSize int) ([]*models.Export, int64, error) {
+	var total int64
+	_ = s.pool.QueryRow(ctx, `SELECT COUNT(*) FROM render.exports WHERE deleted_at IS NULL`).Scan(&total)
+
+	rows, err := s.pool.Query(ctx,
+		`SELECT `+exportCols+`
+		 FROM render.exports WHERE deleted_at IS NULL
+		 ORDER BY produce_date DESC LIMIT $1 OFFSET $2`,
+		pageSize, (page-1)*pageSize)
+	if err != nil {
+		return nil, 0, err
+	}
+	defer rows.Close()
+	exports, err := scanExports(rows)
+	return exports, total, err
+}
+
+// GetExportByIDAny fetches an export regardless of owner (admin).
+func (s *Store) GetExportByIDAny(ctx context.Context, id uuid.UUID) (*models.Export, error) {
+	rows, err := s.pool.Query(ctx,
+		`SELECT `+exportCols+` FROM render.exports WHERE id = $1 AND deleted_at IS NULL`, id)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	exports, err := scanExports(rows)
+	if err != nil {
+		return nil, err
+	}
+	if len(exports) == 0 {
+		return nil, fmt.Errorf("export not found")
+	}
+	return exports[0], nil
+}
+
+// SoftDeleteExportAny deletes an export regardless of owner (admin).
+func (s *Store) SoftDeleteExportAny(ctx context.Context, id uuid.UUID) error {
+	tag, err := s.pool.Exec(ctx,
+		`UPDATE render.exports SET deleted_at = NOW() WHERE id = $1 AND deleted_at IS NULL`, id)
+	if err != nil {
+		return err
+	}
+	if tag.RowsAffected() == 0 {
+		return fmt.Errorf("export not found")
+	}
+	return nil
+}