refactor(blog): factory-style use cases + per-use-case controllers + getArticleBySlug

- Use cases (create-article, get-articles, get-article-by-slug NEW) → factory functions
- Controllers split: articles.controller.ts → 3 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: §6.2

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

packages/blog/src/application/use-cases/get-articles.use-case.ts

@@ -1,16 +1,15 @@
 import type { Article } from "../../entities/models/article";
-import { blogContainer } from "../../di/container";
-import { BLOG_SYMBOLS } from "../../di/symbols";
 import type { IArticlesRepository } from "../repositories/articles.repository.interface";
 
-export async function getArticlesUseCase(options?: {
-  status?: string;
-  authorId?: string;
-  limit?: number;
-  offset?: number;
-}): Promise<Article[]> {
-  const repo = blogContainer.get<IArticlesRepository>(
-    BLOG_SYMBOLS.IArticlesRepository,
-  );
-  return repo.getArticles(options);
-}
+export type IGetArticlesUseCase = ReturnType<typeof getArticlesUseCase>;
+
+export const getArticlesUseCase =
+  (articlesRepository: IArticlesRepository) =>
+  async (options?: {
+    status?: string;
+    authorId?: string;
+    limit?: number;
+    offset?: number;
+  }): Promise<Article[]> => {
+    return articlesRepository.getArticles(options);
+  };