Interested in contributing custom invoice templates

[AIGirl10]

Hi,

First of all, really appreciate your work on invoice-cli.

We would also love to contribute back to the repository, especially around adding support for custom invoice templates.

Could you please guide us on:

• the current architecture for templates,
• any developer documentation available,
• and the recommended way to add new custom templates?

If contribution guidelines or internal design notes exist, that would help us contribute properly.