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.test.ts

@@ -0,0 +1,29 @@
+import { describe, it, expect, beforeEach } from "vitest";
+import { navItemFactory } from "@/__factories__/nav-item.factory";
+
+describe("navItemFactory", () => {
+  beforeEach(() => navItemFactory.reset());
+
+  it("returns a HeaderItem with stable defaults", () => {
+    const item = navItemFactory.build();
+    expect(item.label).toBe("Item 1");
+    expect(item.href).toBe("/item-1");
+    expect(item.external).toBe(false);
+  });
+
+  it("applies overrides", () => {
+    const item = navItemFactory.build({ label: "Home", href: "/", external: true });
+    expect(item.label).toBe("Home");
+    expect(item.href).toBe("/");
+    expect(item.external).toBe(true);
+  });
+
+  it("increments sequence per build", () => {
+    const a = navItemFactory.build();
+    const b = navItemFactory.build();
+    expect(a.label).toBe("Item 1");
+    expect(b.label).toBe("Item 2");
+    expect(a.href).toBe("/item-1");
+    expect(b.href).toBe("/item-2");
+  });
+});