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/marketing-pages/src/application/repositories/pages-repository.interface.ts

@@ -1,4 +1,4 @@
-import type { Page } from "../../entities/page";
+import type { Page } from "../../entities/models/page";
 
 export interface IPagesRepository {
   getPageBySlug(slug: string): Promise<Page | undefined>;

packages/marketing-pages/src/application/repositories/site-settings-repository.interface.ts

@@ -1,4 +1,4 @@
-import type { SiteSettings } from "../../entities/site-settings";
+import type { SiteSettings } from "../../entities/models/site-settings";
 
 export interface ISiteSettingsRepository {
   getSiteSettings(): Promise<SiteSettings>;

packages/marketing-pages/src/application/use-cases/get-page-by-slug.use-case.ts

@@ -1,4 +1,4 @@
-import type { Page } from "../../entities/page";
+import type { Page } from "../../entities/models/page";
 import { marketingPagesContainer } from "../../di/container";
 import { MARKETING_PAGES_SYMBOLS } from "../../di/symbols";
 import type { IPagesRepository } from "../repositories/pages-repository.interface";

packages/marketing-pages/src/application/use-cases/get-site-settings.use-case.ts

@@ -1,4 +1,4 @@
-import type { SiteSettings } from "../../entities/site-settings";
+import type { SiteSettings } from "../../entities/models/site-settings";
 import { marketingPagesContainer } from "../../di/container";
 import { MARKETING_PAGES_SYMBOLS } from "../../di/symbols";
 import type { ISiteSettingsRepository } from "../repositories/site-settings-repository.interface";