feat: Add community package guidelines + top level community node

[zastrowm]

Description

Add a top-level Community section in the documentation - the purpose is two-fold:

1. add a place to add packaging guidelines
2. showcase community-contributed packages

For (1): Added community/community-packages.md. This includes detailed guidance for creating, publishing, and featuring community packages, along with clear examples and best practices for model providers and tools.

For (2): Community model providers (Cohere, CLOVA Studio) have been moved to a dedicated community/model-providers/ section for better organization.

Note

Clova-studio and Cohere files were moved not rewritten; the diff is slightly misleading; this commit is an easier to understand diff

Notes:

• Backward Compatibility Workaround: To avoid breaking existing links, I added a redirect mechanism using markdown links combined with JavaScript - we automatically redirect to the new community sections using a custom auto-redirect.js element that handles client-side redirects after a 1-second delay. I did this to let mkdocs generate the correct links while JavaScript does the actual redirection to let people see the change. I didn't use the mkdocs redirect plugin as it has content flashing - I'm banking on the new CMS to avoid this hack.
• I'm hoping that more content will fill out the community section as we get more contributions.
• I added cohere as a Community Model Provider even though it uses OpenAI underneath the hood because I feel like we can add additional OpenAI providers like this going forward.

Type of Change

• New content addition

Screenshots

The screenshots are slightly-of-out-date in that the Community node is now after Examples

Checklist

• I have read the CONTRIBUTING document
• My changes follow the project's documentation style
• I have tested the documentation locally using mkdocs serve
• Links in the documentation are valid and working
• Images/diagrams are properly sized and formatted
• All new and existing tests pass

Additional Notes

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