refactor(marketing-pages): factory-style use cases + per-use-case controllers

- Use cases (get-page-by-slug, get-site-settings) → factory functions with I*UseCase aliases
- Controllers split: pages.controller.ts → 2 single-responsibility files
- DI module wires factories with .toDynamicValue()
- tRPC router resolves controllers via container

Refactor log: §2, §3, §4.1, §4.2, §5.1
Spec: §6.3

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

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

@@ -1,25 +1,12 @@
-import { beforeEach, describe, expect, it } from "vitest";
-import { marketingPagesContainer } from "@/di/container";
-import { MARKETING_PAGES_SYMBOLS } from "@/di/symbols";
+import { describe, it, expect } from "vitest";
+import { getSiteSettingsUseCase } from "@/application/use-cases/get-site-settings.use-case";
 import { MockSiteSettingsRepository } from "@/infrastructure/repositories/site-settings.repository.mock";
-import type { ISiteSettingsRepository } from "@/application/repositories/site-settings.repository.interface";
-import { getSiteSettingsUseCase } from "./get-site-settings.use-case";
 
 describe("getSiteSettingsUseCase", () => {
-  let repo: MockSiteSettingsRepository;
-
-  beforeEach(() => {
-    if (marketingPagesContainer.isBound(MARKETING_PAGES_SYMBOLS.ISiteSettingsRepository)) {
-      marketingPagesContainer.unbind(MARKETING_PAGES_SYMBOLS.ISiteSettingsRepository);
-    }
-    repo = new MockSiteSettingsRepository();
-    marketingPagesContainer
-      .bind<ISiteSettingsRepository>(MARKETING_PAGES_SYMBOLS.ISiteSettingsRepository)
-      .toConstantValue(repo);
-  });
-
   it("returns the seeded site settings", async () => {
-    const result = await getSiteSettingsUseCase();
+    const repo = new MockSiteSettingsRepository();
+    const useCase = getSiteSettingsUseCase(repo);
+    const result = await useCase();
     expect(result.siteName).toBe("My App");
   });
 });