fix(i18n): ship i18n data as a JSON block so CSP cannot block it

window.__wrnI18n was undefined in development: the payload shipped as an
executable inline script, and a document's CSP nonce is fixed at load, so
any such script arriving from a later response is blocked. Client
translations and language switching silently had no data.

The payload is now a type="application/json" block, which the browser
never executes and script-src therefore never applies to. The i18n
runtime, CSR navigation, and HMR all read the block instead of matching
window.__wrnI18n= with a regex.

Pages now render zero executable inline scripts, so an inline script-src
violation is structurally impossible rather than merely unobserved. Zero
framework JavaScript on island-free routes is unaffected: the block is
inert data, and nothing loads to read it unless the page needs it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/i18n/test/i18n-data-block.test.ts

@@ -0,0 +1,25 @@
+import { expect, test } from "bun:test";
+import { I18N_RUNTIME, renderI18nData, renderI18nDataTag, resolveI18n } from "../src/index.ts";
+
+const i18n = resolveI18n({ en: { hello: "Hello" }, es: { hello: "Hola" } }, { default: "en" });
+
+test("the i18n payload is plain JSON, not an assignment", () => {
+  const data = renderI18nData(i18n, "en");
+  expect(() => JSON.parse(data)).not.toThrow();
+  expect(data).not.toContain("window.__wrnI18n");
+});
+
+test("the data tag is a non-executable JSON block", () => {
+  // An executable inline script is subject to script-src and gets blocked
+  // whenever the document's CSP nonce came from a different response, which is
+  // what left window.__wrnI18n undefined. A JSON block is never executed.
+  const tag = renderI18nDataTag(i18n, "es");
+  expect(tag).toContain('type="application/json"');
+  expect(tag).toContain("data-wrn-i18n");
+  expect(tag).not.toContain("nonce=");
+  expect(tag).toContain("Hola");
+});
+
+test("the i18n runtime reads the data block instead of relying on an inline assignment", () => {
+  expect(I18N_RUNTIME).toContain('script[type="application/json"][data-wrn-i18n]');
+});