feat(completion): Add in codex.nvim

[Uzaaft]

This might be one of the case where we need to prefix the author to the name, since I recon it could be a flood of codex.nvim plugins. WDYT? @AstroNvim/astrocommunity-maintainers

[github-actions]

Review Checklist

Does this PR follow the [Contribution Guidelines](development guidelines)? Following is a partial checklist:

Proper conventional commit scoping:

• If you are adding a new plugin, the scope would be the name of the category it is being added into. ex. feat(utility): added noice.nvim plugin

• If you are modifying a pre-existing plugin or pack, the scope would be the name of the plugin folder. ex. fix(noice-nvim): fix LSP handler error

• Pull request title has the appropriate conventional commit type and scope where the scope is the name of the pre-existing directory in the project as described above

• README is properly formatted and uses fenced in links with <url> unless they are inside a [title](url)

• Entry returns a single plugin spec with the new plugin as the only top level spec (not applicable for recipes or packs).

• Proper usage of opts table rather than setting things up with the config function.

• Proper usage of specs table for all specs that are not dependencies of a given plugin (not applicable for recipes or packs).

[azdanov]

Yeah, would be good idea to add the author. It's already confusing with copilot.nvim and copilot.vim for some people 😄

[johnseth97]

There is still some work to be done yet on the plugin, planning on pushing out some tests today and checking compliance with the neovim spec.

[johnseth97]

Update: Plugin is finalized and ready for release

Plugin has also been updated with an auto-install flag, which will auto install codex via npm if not available. Otherwise it will notify the user and ask them to run the command npm i -g codex, as the default behavior. Codex will notify the user if they need to set $OPENAI_API_KEY env.

Depending on how hands-off we want the default config to be for the user, I would recommend setting autoinstall=true in the opts table

The default plugin configuration is as follows, all can be overridden with the opts table in the plugin setup call as shown in the plugin repo

opts = {
    keymaps = {}, -- disable internal mapping
    border = 'rounded', -- or 'double'
    width = 0.8,
    height = 0.8,
    autoinstall = true,
  }