New integration: Dev.to publishing

[Dumebii]

Background

Ozigi generates blog posts. Dev.to has a public REST API for publishing articles and is heavily used by the developer audience we're targeting.

API reference

• Docs: https://developers.forem.com/api
• Auth: API key (simpler than OAuth — just store and use)
• Publish endpoint: POST https://dev.to/api/articles

What's needed

1. API key storage — User inputs their Dev.to API key in account settings
2. Publish route — POST /api/publish/devto following the same pattern as existing publish routes in app/api/publish/
3. Format mapping — Dev.to accepts markdown; map Ozigi's long-form output to their article schema: title, body_markdown, tags[], published (bool)
4. UI — Add Dev.to to the publish options next to long-form output

Acceptance criteria

• User can add/remove their Dev.to API key in settings
• Blog post can be published as a draft or as a live article
• Tags are populated from the generation context where possible
• Error states handled — invalid key, rate limit, network failure
• Follows the same response shape as existing publish routes