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/infrastructure/repositories/media.repository.mock.ts

@@ -0,0 +1,29 @@
+import "reflect-metadata";
+import { injectable } from "inversify";
+
+import type { IMediaRepository } from "../../application/repositories/media.repository.interface";
+import type { Media } from "../../entities/models/media";
+
+@injectable()
+export class MockMediaRepository implements IMediaRepository {
+  private _media: Media[] = [];
+
+  /** Test helper — seeds the in-memory store directly. */
+  async _store(media: Media): Promise<void> {
+    this._media.push(media);
+  }
+
+  async getMedia(id: string): Promise<Media | undefined> {
+    return this._media.find((m) => m.id === id);
+  }
+
+  async listMedia(opts?: { limit?: number; offset?: number }): Promise<Media[]> {
+    const offset = opts?.offset ?? 0;
+    const limit = opts?.limit ?? 50;
+    return this._media.slice(offset, offset + limit);
+  }
+
+  async deleteMedia(id: string): Promise<void> {
+    this._media = this._media.filter((m) => m.id !== id);
+  }
+}