refactor(api): rename DTO classes to Request for clarity

api.py

@@ -1087,7 +1087,7 @@ async def rechercher_articles(query: Optional[str] = Query(None)):
         raise HTTPException(500, str(e))
 
 @app.post("/articles", status_code=status.HTTP_201_CREATED, tags=["Articles"])
-def creer_article(article: ArticleCreateDTO):
+def creer_article(article: ArticleCreateRequest):
     """
     ➕ Création d'un article dans Sage
     
@@ -1117,7 +1117,7 @@ def creer_article(article: ArticleCreateDTO):
 
 
 @app.put("/articles/{reference}", tags=["Articles"])
-def modifier_article(reference: str, article: ArticleUpdateDTO):
+def modifier_article(reference: str, article: ArticleUpdateRequest):
     """
     ✏️ Modification d'un article dans Sage