docs: rewrite CONTRIBUTING.md with comprehensive development guide

Requested by @ntindle

The existing CONTRIBUTING.md was a stub pointing to an outdated wiki.
This rewrites it as a proper human-friendly guide, pulling from our
detailed CLAUDE.md files that previously only served AI tools.

Changes:
- Root CONTRIBUTING.md: Full rewrite with setup, dev commands, testing,
  PR process, conventional commits, and docs contribution
- docs/platform/SUMMARY.md: Add Contributing section with links
- docs/platform/contributing/README.md: Hub page linking to guides

The frontend CONTRIBUTING.md (already comprehensive) is linked rather
than duplicated.

CONTRIBUTING.md

@@ -1,38 +1,14 @@
-# AutoGPT Contribution Guide
-If you are reading this, you are probably looking for the full **[contribution guide]**,
-which is part of our [wiki].
+# Contributing to AutoGPT
 
-[contribution guide]: https://github.com/Significant-Gravitas/AutoGPT/wiki/Contributing
-[wiki]: https://github.com/Significant-Gravitas/AutoGPT/wiki
-[roadmap]: https://github.com/Significant-Gravitas/AutoGPT/discussions/6971
-[kanban board]: https://github.com/orgs/Significant-Gravitas/projects/1
+For the full contribution guide, see [`CONTRIBUTING.md`](https://github.com/Significant-Gravitas/AutoGPT/blob/dev/CONTRIBUTING.md) in the repository root.
 
-## Contributing to the AutoGPT Platform Folder
-All contributions to [the autogpt_platform folder](https://github.com/Significant-Gravitas/AutoGPT/blob/master/autogpt_platform) will be under our [Contribution License Agreement](https://github.com/Significant-Gravitas/AutoGPT/blob/master/autogpt_platform/Contributor%20License%20Agreement%20(CLA).md). By making a pull request contributing to this folder, you agree to the terms of our CLA for your contribution. All contributions to other folders will be under the MIT license.
+## Quick Links
 
-## In short
-1. Avoid duplicate work, issues, PRs etc.
-2. We encourage you to collaborate with fellow community members on some of our bigger
-   [todo's][roadmap]!
-   * We highly recommend to post your idea and discuss it in the [dev channel].
-3. Create a draft PR when starting work on bigger changes.
-4. Adhere to the [Code Guidelines]
-5. Clearly explain your changes when submitting a PR.
-6. Don't submit broken code: test/validate your changes.
-7. Avoid making unnecessary changes, especially if they're purely based on your personal
-   preferences. Doing so is the maintainers' job. ;-)
-8. Please also consider contributing something other than code; see the
-   [contribution guide] for options.
+- **Full Guide:** [CONTRIBUTING.md](https://github.com/Significant-Gravitas/AutoGPT/blob/dev/CONTRIBUTING.md)
+- **Frontend Guide:** [frontend/CONTRIBUTING.md](https://github.com/Significant-Gravitas/AutoGPT/blob/dev/autogpt_platform/frontend/CONTRIBUTING.md)
+- **Block SDK Guide:** [Block SDK](https://github.com/Significant-Gravitas/AutoGPT/blob/dev/docs/platform/block-sdk-guide.md)
+- **Discord:** [discord.gg/autogpt](https://discord.gg/autogpt)
 
-[dev channel]: https://discord.com/channels/1092243196446249134/1095817829405704305
-[code guidelines]: https://github.com/Significant-Gravitas/AutoGPT/wiki/Contributing#code-guidelines
+## Contributing to Docs
 
-If you wish to involve with the project (beyond just contributing PRs), please read the
-wiki page about [Catalyzing](https://github.com/Significant-Gravitas/AutoGPT/wiki/Catalyzing).
-
-In fact, why not just look through the whole wiki (it's only a few pages) and
-hop on our Discord. See you there! :-)
-
-❤️ & 🔆
-The team @ AutoGPT
-https://discord.gg/autogpt
+Documentation lives in the `docs/` directory on the `gitbook` branch. See the [docs contribution guide](contribute/index.md) for how to edit and submit changes.

docs/platform/SUMMARY.md

@@ -33,6 +33,12 @@
 * [API Introduction](integrating/api-guide.md)
 * [OAuth & SSO](integrating/oauth-guide.md)
 
+## Contributing
+
+* [Contributing Guide](contributing/README.md)
+* [OAuth Integration Flow](contributing/oauth-integration-flow.md)
+* [Testing](contributing/tests.md)
+
 ## Changelog
 
 * [What's New](changelog/README.md)

docs/platform/contributing/README.md

@@ -0,0 +1,18 @@
+# Contributing
+
+Want to contribute to AutoGPT? Welcome!
+
+For the complete contributing guide, see the [CONTRIBUTING.md](https://github.com/Significant-Gravitas/AutoGPT/blob/dev/CONTRIBUTING.md) in the repository root. It covers:
+
+- Repository structure and setup
+- Backend and frontend development
+- Testing strategy
+- Pull request process and conventions
+- Documentation contributions
+
+## Platform-Specific Guides
+
+- [OAuth Integration Flow](oauth-integration-flow.md) — How to add OAuth providers
+- [Testing](tests.md) — Playwright E2E testing setup and patterns
+- [Block SDK Guide](../block-sdk-guide.md) — Building custom blocks
+- [Frontend Contributing Guide](https://github.com/Significant-Gravitas/AutoGPT/blob/dev/autogpt_platform/frontend/CONTRIBUTING.md) — Detailed frontend patterns and conventions