feat: create standalone CLI for cocoindex

[lemorage]

This is a breaking change, and may resolve #417.

We create a standalone CLI for cocoindex. For compatibility reasons, we mark main_fn as deprecated. So, users can still use @cocoindex.main_fn() in their programs, but when running python main.py cocoindex <command>, the deprecation warning will be shown instead.

Now, in the new CLI, we will use cocoindex <command> [options] --app main.py to run the CLI program directly.

A lot of examples and docs will then be outdated and need to be updated accordingly. I will start on those if all the changes in this PR are confirmed.

[badmonster0]

Really awesome! Thanks for making this happen!

[badmonster0]

Another thing I just notice - which will be needed by migrating existing examples - is about loading of the .env files.

Previously they're loaded by examples' main module (under the if __name__ == "__main__": condition), but they're no longer executed when we invoke this standalone CLI.

So I think this standalone CLI may need to be able to load .env file, and we may also add a --env_file flag to allow override (example: flask CLI is doing the similar).

Let me know if you have any other thoughts. Thanks!

[lemorage]

Nice catch!

[badmonster0]

Thanks a lot for making it happen! This is a big thing!

[lemorage]

Thanks for all the help along the way! I've created another PR accounting for the docs' changes to the standalone CLI.

[badmonster0]

hi @lemorage thank you so much for all your contribution with cocoindex, we love all your contributions and made a section for you on the latest release note https://cocoindex.io/blogs/cocoindex-changelog-2025-05-31/#lemorage