lb4 relation doesn't find models

還沒有人認領這個 Issue。

### Describe the bug

I have a project with a lot of models. I organized the models in "sub directories" inside "models" directory.
The "export" is working properly and all the project is working.
What is not working is the possibility to add repositories, relations or anything else
"lb4 relation" stops with an error "Generation is aborted: Error: No models found in ".../src/models"."
I expect the script to be capable to look for models also inside according to what is available in "index.ts" from "models" directory.

### Logs

_No response_

### Additional information

_No response_

### Reproduction

https://github.com/danysz/demo-lb4-cli-model-not-found

先從 `lb4 relation` 命令和 issue 中連結的重現專案開始，然後檢查它如何掃描 `src/models` 以及如何使用該目錄的 `index.ts`。當組織在子目錄中的模型能夠被發現並用於 relation 或 repository 產生，而不是產生「No models found.」時，這項工作就完成了。

由索引模型根據 Issue 內容生成。