fix(features): address Task 3 code review feedback

- Add navItemFactory to navigation (spec §5.1 — was missing)
- Refactor blog/router.test.ts to use articleFactory (eliminate new Date())
- headerFactory uses sequence for logoId (deterministic buildList output)
- Align media/tsconfig.json with other features (jsx + tests/ include)
- Refactor auth/container.test.ts to use userFactory

Reviewer: superpowers:code-reviewer (Task 3 of Plan 7).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/navigation/src/__factories__/nav-item.factory.ts

@@ -0,0 +1,8 @@
+import { defineFactory } from "@repo/core-testing/factory";
+import type { HeaderItem } from "../entities/header.js";
+
+export const navItemFactory = defineFactory<HeaderItem>(({ sequence }) => ({
+  label: `Item ${sequence}`,
+  href: `/item-${sequence}`,
+  external: false,
+}));