refactor(features): split entities into models/ + errors/ subdirs

All 5 features (auth, blog, marketing-pages, navigation; media has no
entities yet) now follow Lazar's pattern:
- entities/<x>.ts → entities/models/<x>.ts
- entities/errors.ts → entities/errors/<domain>.ts + errors/common.ts

Updates all import paths across factories, contracts, tests, use cases,
controllers, repositories, integrations, and src/index.ts exports.

navigation divergence: had no errors.ts; errors/header.ts +
errors/common.ts added as new forward-looking stubs.

Refactor log: docs/superpowers/refactor-logs/2026-05-05-lazar-pattern-conformance.md
Spec: §5, §9.3

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/navigation/src/entities/models/header.test.ts

@@ -0,0 +1,61 @@
+import { describe, expect, it } from "vitest";
+import { headerSchema, headerItemSchema } from "./header";
+
+describe("headerItemSchema", () => {
+  it("accepts a valid nav item", () => {
+    const result = headerItemSchema.parse({
+      label: "Home",
+      href: "/",
+    });
+    expect(result.label).toBe("Home");
+    expect(result.external).toBe(false);
+  });
+
+  it("accepts an external nav item", () => {
+    const result = headerItemSchema.parse({
+      label: "Blog",
+      href: "https://blog.example.com",
+      external: true,
+    });
+    expect(result.external).toBe(true);
+  });
+
+  it("rejects an empty label", () => {
+    expect(() => headerItemSchema.parse({ label: "", href: "/" })).toThrow();
+  });
+
+  it("rejects a label over 64 chars", () => {
+    expect(() =>
+      headerItemSchema.parse({ label: "x".repeat(65), href: "/" }),
+    ).toThrow();
+  });
+
+  it("rejects an empty href", () => {
+    expect(() =>
+      headerItemSchema.parse({ label: "Home", href: "" }),
+    ).toThrow();
+  });
+});
+
+describe("headerSchema", () => {
+  it("accepts a valid header with items", () => {
+    const result = headerSchema.parse({
+      items: [{ label: "Home", href: "/" }],
+    });
+    expect(result.items).toHaveLength(1);
+    expect(result.logoId).toBeUndefined();
+  });
+
+  it("accepts a header with a logoId", () => {
+    const result = headerSchema.parse({
+      logoId: "logo-abc",
+      items: [],
+    });
+    expect(result.logoId).toBe("logo-abc");
+  });
+
+  it("accepts a header with no items", () => {
+    const result = headerSchema.parse({ items: [] });
+    expect(result.items).toHaveLength(0);
+  });
+});

packages/navigation/src/entities/models/header.ts

@@ -0,0 +1,15 @@
+import { z } from "zod";
+
+export const headerItemSchema = z.object({
+  label: z.string().min(1).max(64),
+  href: z.string().min(1),
+  external: z.boolean().default(false),
+});
+
+export const headerSchema = z.object({
+  logoId: z.string().optional(),
+  items: z.array(headerItemSchema),
+});
+
+export type Header = z.infer<typeof headerSchema>;
+export type HeaderItem = z.infer<typeof headerItemSchema>;