Add crawler implementation (Node.js + TypeScript)

- Create crawler project structure
- Implement base crawler class with safety features
- Add crawlers for Ruliweb, Arcalive, DCInside
- Implement utilities: fetcher (with retry logic), logger
- Configure crawling settings (3s delay, max 20 posts/board)
- Add test script and scheduler (30min intervals)

Safety measures:
- 3 second delay between requests
- Exponential backoff retry logic
- Respect robots.txt (DCInside disabled)
- User-Agent and proper headers

Current status:
- Structure complete
- Both Ruliweb and Arcalive return 403 (bot detection)
- Need to decide: Puppeteer, switch targets, or use mock data

src/data/posts.json

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+[]