[TODO Import][Server][Backlog] Share result image generation APIs

[ferneediaz]

Imported from server/TODO.md.

Kanban

• Column: Backlog
• Area: Server

📋 TODO - Share Result Image Generation (LOW PRIORITY)

Generate shareable battle result images for social media.

Task Breakdown:

1. Image Generation

• Create share/ module
• generateResultImage(battleId) — Generate battle result card image
• Include: winner/loser names, rank badges, MMR change, problem title, time taken
• Pre-written trash talk captions (randomized pool)
• Use @vercel/og or canvas (satori) for server-side image generation
• Success Criteria: Image generates correctly ✅

2. API

• GET /api/battles/:id/share-image — Return generated image (PNG)
• GET /api/battles/:id/share — Return public shareable data (JSON for OG tags)
• Success Criteria: Image accessible via URL ✅

3. Tests

• Image generation tests
• Success Criteria: Share image tests passing ✅

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