test: enforce per-directory coverage thresholds

entities + use-cases + controllers must hit 100% (95% branches).
Project-wide baseline remains 80/75/80/80. Tightening these directories
reflects the architectural intent: these are the pure-logic layers and
should be exhaustively tested.

Added @vitest/coverage-v8@^3 to core-typescript, auth, blog,
marketing-pages, and navigation devDependencies.

Excluded from coverage (legitimately untestable):
- src/di/bind-production.ts — InversifyJS startup bootstrap
- src/application/repositories/** — pure TypeScript interfaces
- src/application/services/** — pure TypeScript interfaces (auth)
- src/integrations/cms/** — declarative Payload CMS config
- src/entities/cookie.ts — pure type aliases (auth)
- src/ui/** — React Query helpers, integration-tested in apps

Tests added (6 new files / 1 extended):
- auth/src/entities/errors.test.ts — UnauthenticatedError, UnauthorizedError,
  AuthenticationError, InputParseError constructors
- blog/src/entities/errors.test.ts — ArticleNotFoundError (default + custom
  message), InputParseError
- marketing-pages/src/entities/errors.test.ts — PageNotFoundError, InputParseError
- marketing-pages/src/entities/site-settings.test.ts — siteSettingsSchema
  (valid, no description, empty name rejection)
- navigation/src/entities/header.test.ts — headerItemSchema and headerSchema
  validation paths
- navigation/src/.../payload-header.repository.test.ts — logo relation-object,
  scalar-id, null, and null-item-field branches for full branch coverage

Spec: §6.9

packages/navigation/src/infrastructure/repositories/payload-header.repository.test.ts

@@ -1,4 +1,4 @@
-import { describe, vi } from "vitest";
+import { describe, it, expect, vi } from "vitest";
 import { PayloadHeaderRepository } from "@/infrastructure/repositories/payload-header.repository";
 import { headerRepositoryContract, CONTRACT_HEADER_SEED } from "@/__contracts__/header-repository.contract";
 import { stubPayloadConfig } from "@repo/core-testing/payload/stub-config";
@@ -7,10 +7,10 @@ import { stubPayloadConfig } from "@repo/core-testing/payload/stub-config";
 // In-memory Payload stub for header (Global)
 // ---------------------------------------------------------------------------
 
-function buildHeaderStub() {
+function buildHeaderStub(overrides?: Record<string, unknown>) {
   return {
     findGlobal: vi.fn(async () => {
-      return { ...CONTRACT_HEADER_SEED };
+      return { ...CONTRACT_HEADER_SEED, ...overrides };
     }),
   };
 }
@@ -32,4 +32,58 @@ describe("PayloadHeaderRepository", () => {
       return new PayloadHeaderRepository(stubPayloadConfig);
     });
   });
+
+  // ---------------------------------------------------------------------------
+  // Logo field branch coverage
+  // ---------------------------------------------------------------------------
+
+  it("resolves logoId from a relation object ({ id })", async () => {
+    const stub = buildHeaderStub({ logo: { id: "abc-123" } });
+    const { getPayload } = await import("payload");
+    (getPayload as ReturnType<typeof vi.fn>).mockResolvedValue(stub);
+
+    const repo = new PayloadHeaderRepository(stubPayloadConfig);
+    const header = await repo.getHeader();
+
+    expect(header.logoId).toBe("abc-123");
+  });
+
+  it("resolves logoId from a scalar id (string)", async () => {
+    const stub = buildHeaderStub({ logo: "scalar-id" });
+    const { getPayload } = await import("payload");
+    (getPayload as ReturnType<typeof vi.fn>).mockResolvedValue(stub);
+
+    const repo = new PayloadHeaderRepository(stubPayloadConfig);
+    const header = await repo.getHeader();
+
+    expect(header.logoId).toBe("scalar-id");
+  });
+
+  it("resolves logoId as undefined when logo is null", async () => {
+    const stub = buildHeaderStub({ logo: null });
+    const { getPayload } = await import("payload");
+    (getPayload as ReturnType<typeof vi.fn>).mockResolvedValue(stub);
+
+    const repo = new PayloadHeaderRepository(stubPayloadConfig);
+    const header = await repo.getHeader();
+
+    expect(header.logoId).toBeUndefined();
+  });
+
+  it("maps null item fields to empty strings and false", async () => {
+    const stub = {
+      findGlobal: vi.fn(async () => ({
+        items: [{ label: null, href: null, external: null }],
+      })),
+    };
+    const { getPayload } = await import("payload");
+    (getPayload as ReturnType<typeof vi.fn>).mockResolvedValue(stub);
+
+    const repo = new PayloadHeaderRepository(stubPayloadConfig);
+    const header = await repo.getHeader();
+
+    expect(header.items[0]?.label).toBe("");
+    expect(header.items[0]?.href).toBe("");
+    expect(header.items[0]?.external).toBe(false);
+  });
 });