refactor(naming): harmonize controller and route file names

- Delete product.controller.js, merge unique functions into products.controller.js
- Rename user.controller.js → users.controller.js, user.routes.js → users.routes.js
- Remove dead herowars/herowars.routes.js reference from herowars index
- Update all import paths accordingly

src/routes/api/ecommerce/product.routes.js

@@ -7,7 +7,7 @@ const {
     deleteFavoriteProduct,
     deleteProduct,
     updateProduct,
-} = require('../../../controllers/product.controller');
+} = require('../../../controllers/products.controller');
 const auth = require('../../../middlewares/auth');
 
 const productRouter = express.Router();