feat(email-renderer): render countdown images across email targets

packages/email-renderer/src/email.ts

@@ -106,18 +106,28 @@ export async function renderEmail(
     direction?: "ltr" | "rtl";
     variables?: Record<string, unknown>;
     requireVariables?: boolean;
+    countdownImageUrl?: string;
   } = {},
 ): Promise<Result<EmailRenderBundle>> {
   const personalized = resolveDocumentVariables(document, emailKind.variables, options.variables, {
     requireValues: options.requireVariables,
   });
   if (!personalized.ok) return personalized;
+  if (options.countdownImageUrl) {
+    try {
+      const url = new URL(options.countdownImageUrl);
+      if (url.username || url.password || (url.protocol !== "https:" && !(url.protocol === "http:" && (url.hostname === "localhost" || url.hostname.endsWith(".localhost"))))) throw new Error();
+    } catch {
+      return { ok: false, errors: [{ code: "countdown.endpoint", message: "Countdown images require HTTPS (or a local development host).", severity: "error" }] };
+    }
+  }
   const source = personalized.value;
   const registry = registryForKind(emailKind).freeze();
   const base = {
     locale: options.locale ?? "en",
     timezone: options.timezone ?? "UTC",
     direction: options.direction ?? "ltr",
+    countdownImageUrl: options.countdownImageUrl,
   };
   const [htmlResult, textResult, mjmlResult] = await Promise.all([
     renderTree(source, emailKind, registry, { ...base, target: "emailHtml", data: options.variables }),