Centralize palette block creation in the email framework

packages/email-renderer/test/create.test.ts

@@ -0,0 +1,18 @@
+import { expect, test } from "bun:test";
+import { createEmailBlock } from "../src/create.ts";
+import { emailCoreBlocks } from "../src/blocks.ts";
+
+test("palette factory produces schema-valid independent blocks with injected IDs and time", () => {
+  let sequence = 0;
+  for (const definition of emailCoreBlocks.filter(block => /^(content|commerce)\./.test(block.manifest.type))) {
+    const context = { id: () => `node-${++sequence}`, now: Date.parse("2026-09-05T00:00:00Z") };
+    const first = createEmailBlock(definition.manifest.type, context), second = createEmailBlock(definition.manifest.type, context);
+    expect(definition.manifest.props.parse(first.props).ok).toBe(true);
+    expect(first.id).not.toBe(second.id);
+    expect(first.props).toEqual(second.props);
+    expect(first.props).not.toBe(second.props);
+    expect(first.version).toBe(definition.manifest.version);
+    if (first.type === "content.countdown") expect(first.props.deadline).toBe("2026-09-06T00:00:00.000Z");
+  }
+  expect(() => createEmailBlock("untrusted.block", { id: () => "id" })).toThrow();
+});