fix(email): preserve personalization tokens for template rendering

packages/email-renderer/src/email.ts

@@ -110,6 +110,8 @@ export async function renderEmail(
     direction?: "ltr" | "rtl";
     variables?: Record<string, unknown>;
     requireVariables?: boolean;
+    /** Preserve allowlisted tokens and fallbacks for template export, never for final delivery. */
+    preserveVariables?: boolean;
     countdownImageUrl?: string;
     /** Trusted host injection; never sourced from the editable document. */
     ampValidator?: (content: string) => Promise<ValidationReport>;
@@ -118,6 +120,7 @@ export async function renderEmail(
 ): Promise<Result<EmailRenderBundle>> {
   const personalized = resolveDocumentVariables(document, emailKind.variables, options.variables, {
     requireValues: options.requireVariables,
+    preserveTokens: options.preserveVariables,
   });
   if (!personalized.ok) return personalized;
   if (options.countdownImageUrl) {