feat(media): full Clean Architecture scaffold

Media is now a complete vertical-feature package mirroring auth/blog
structure: entities (models + errors), application (repositories +
use-cases), infrastructure (real Payload-backed + mock siblings),
interface-adapters (per-use-case controllers), DI (symbols + module +
container + bind-production), integrations/api (mediaRouter), factory,
contract suite, and feature integration tests.

Wired into:
- packages/core-api/src/root.ts (added `media: mediaRouter`)
- apps/web-next/src/server/bind-production.ts (calls bindProductionMedia)
- tsconfig.base.json (added @repo/media/api and ./di/bind-production aliases)

56 new tests in @repo/media (13 test files); core-api router test updated
to assert media. procedures. All 26 turbo tasks green.

Refactor log: §2, §4.1, §4.2, §5.1, §6.1
Spec: §6.5

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

packages/media/src/application/use-cases/get-media.use-case.ts

@@ -0,0 +1,15 @@
+import { MediaNotFoundError } from "../../entities/errors/media";
+import type { Media } from "../../entities/models/media";
+import type { IMediaRepository } from "../repositories/media.repository.interface";
+
+export type IGetMediaUseCase = ReturnType<typeof getMediaUseCase>;
+
+export const getMediaUseCase =
+  (mediaRepository: IMediaRepository) =>
+  async (input: { id: string }): Promise<Media> => {
+    const media = await mediaRepository.getMedia(input.id);
+    if (!media) {
+      throw new MediaNotFoundError(`Media with id "${input.id}" not found`);
+    }
+    return media;
+  };