feat: establish TypeScript-aware frontend tooling

tests/fixtures/security/allowed/safe-text.tsx

@@ -0,0 +1,3 @@
+export function SafeTextFixture({ value }: Readonly<{ value: string }>) {
+  return <p>{value}</p>;
+}

tests/fixtures/security/forbidden/raw-html.tsx

@@ -0,0 +1,3 @@
+export function UnsafeHtmlFixture({ value }: Readonly<{ value: string }>) {
+  return <div dangerouslySetInnerHTML={{ __html: value }} />;
+}