AI Feature 2: AI Changelog Writer

[aliamerj]

1. Fetch the roadmap item (title, description)
2. Fetch linked feedback posts (titles, descriptions, upvote counts)
3. Call OpenAI to generate a changelog entry
4. Return { title: string, content: string (HTML), category: string }
5. Save to Changelog with aiDrafted: true, publishedAt: null (draft)
6. Return the new changelog entry ID so dashboard can redirect to editor

System prompt for changelog writer:
"You are writing a changelog entry for [productName].
Product context: [productContext]
The team just completed: [roadmapItem title and description]
This was requested by users who said: [linked feedback titles]
Write a clear, friendly changelog entry from the user's perspective.
Format: Return JSON { title: string, content: string (HTML paragraphs),
category: 'new_feature' | 'improvement' | 'bug_fix' }
Keep it concise — 2-3 short paragraphs max. Focus on user benefit, not technical details."

Connect this to the roadmap "Done" flow: when user clicks "Yes" to generate changelog,