refactor(marketing-pages): unify use-case I/O schemas + presenter + feature error map

Per Plan 9 (spec R1-R28):
- Use cases: input + output schemas (getPageBySlug, getSiteSettings).
  Site-settings input is z.object({}).strict() per R5 (uniform input).
- Controllers: unknown input + identity presenter; void output not
  applicable (both use cases return data).
- New integrations/api/procedures.ts with marketingPagesProcedure
  ([InputParseError → BAD_REQUEST], [PageNotFoundError → NOT_FOUND]).
- Router uses marketingPagesProcedure + .input(xInputSchema).
- src/index.ts: remove pageBySlugQuery/siteSettingsQuery; export
  schemas + types + IUseCase/IController aliases.
- src/ui/index.ts (NEW); package.json adds ./ui subpath.
- R25 output-validation tests + R26 router error-mapping test.

Refactor log: §1, §2, §3.1, §3.2, §3.3, §5.1, §5.2, §6.1, §6.2
Spec: R1–R6, R8–R15, R18–R20, R22–R26

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

@@ -1,4 +1,5 @@
 import { describe, it, expect } from "vitest";
+import { ZodError } from "zod";
 import { getPageBySlugUseCase } from "@/application/use-cases/get-page-by-slug.use-case";
 import { MockPagesRepository } from "@/infrastructure/repositories/pages.repository.mock";
 
@@ -16,4 +17,23 @@ describe("getPageBySlugUseCase", () => {
     const result = await useCase({ slug: "missing-page" });
     expect(result).toBeUndefined();
   });
+
+  it("(R25) throws ZodError when repository returns malformed page data", async () => {
+    const repo = new MockPagesRepository([
+      {
+        id: "p-bad",
+        title: "",
+        slug: "bad-page",
+        hero: { heading: "" },
+        layout: [],
+        status: "published",
+        publishedAt: null,
+        seo: { title: "" },
+        createdAt: new Date(),
+        updatedAt: new Date(),
+      } as never,
+    ]);
+    const useCase = getPageBySlugUseCase(repo);
+    await expect(useCase({ slug: "bad-page" })).rejects.toBeInstanceOf(ZodError);
+  });
 });

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

@@ -1,10 +1,23 @@
-import type { Page } from "../../entities/models/page";
+import { z } from "zod";
+
+import { pageSchema } from "../../entities/models/page";
 import type { IPagesRepository } from "../repositories/pages.repository.interface";
 
+// ── Input ────────────────────────────────────────────────────────────────
+export const getPageBySlugInputSchema = z.object({ slug: z.string().min(1) }).strict();
+export type GetPageBySlugInput = z.infer<typeof getPageBySlugInputSchema>;
+
+// ── Output ───────────────────────────────────────────────────────────────
+export const getPageBySlugOutputSchema = pageSchema;
+export type GetPageBySlugOutput = z.infer<typeof getPageBySlugOutputSchema>;
+
+// ── Use case ─────────────────────────────────────────────────────────────
 export type IGetPageBySlugUseCase = ReturnType<typeof getPageBySlugUseCase>;
 
 export const getPageBySlugUseCase =
   (pagesRepository: IPagesRepository) =>
-  async (input: { slug: string }): Promise<Page | undefined> => {
-    return pagesRepository.getPageBySlug(input.slug);
+  async (input: GetPageBySlugInput): Promise<GetPageBySlugOutput | undefined> => {
+    const page = await pagesRepository.getPageBySlug(input.slug);
+    if (!page) return undefined;
+    return getPageBySlugOutputSchema.parse(page);
   };

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

@@ -1,4 +1,5 @@
 import { describe, it, expect } from "vitest";
+import { ZodError } from "zod";
 import { getSiteSettingsUseCase } from "@/application/use-cases/get-site-settings.use-case";
 import { MockSiteSettingsRepository } from "@/infrastructure/repositories/site-settings.repository.mock";
 
@@ -6,7 +7,15 @@ describe("getSiteSettingsUseCase", () => {
   it("returns the seeded site settings", async () => {
     const repo = new MockSiteSettingsRepository();
     const useCase = getSiteSettingsUseCase(repo);
-    const result = await useCase();
+    const result = await useCase({});
     expect(result.siteName).toBe("My App");
   });
+
+  it("(R25) throws ZodError when repository returns malformed site settings", async () => {
+    const malformedRepo = {
+      getSiteSettings: async () => ({ siteName: "" }),
+    };
+    const useCase = getSiteSettingsUseCase(malformedRepo);
+    await expect(useCase({})).rejects.toBeInstanceOf(ZodError);
+  });
 });

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

@@ -1,10 +1,23 @@
-import type { SiteSettings } from "../../entities/models/site-settings";
+import { z } from "zod";
+
+import { siteSettingsSchema } from "../../entities/models/site-settings";
 import type { ISiteSettingsRepository } from "../repositories/site-settings.repository.interface";
 
+// ── Input ────────────────────────────────────────────────────────────────
+export const getSiteSettingsInputSchema = z.object({}).strict();
+export type GetSiteSettingsInput = z.infer<typeof getSiteSettingsInputSchema>;
+
+// ── Output ───────────────────────────────────────────────────────────────
+export const getSiteSettingsOutputSchema = siteSettingsSchema;
+export type GetSiteSettingsOutput = z.infer<typeof getSiteSettingsOutputSchema>;
+
+// ── Use case ─────────────────────────────────────────────────────────────
 export type IGetSiteSettingsUseCase = ReturnType<typeof getSiteSettingsUseCase>;
 
 export const getSiteSettingsUseCase =
   (siteSettingsRepository: ISiteSettingsRepository) =>
-  async (): Promise<SiteSettings> => {
-    return siteSettingsRepository.getSiteSettings();
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  async (_input: GetSiteSettingsInput): Promise<GetSiteSettingsOutput> => {
+    const result = await siteSettingsRepository.getSiteSettings();
+    return getSiteSettingsOutputSchema.parse(result);
   };