Rate limits now configurable via config.toml and ENV variables:
- New [rate_limit] config section with auth/upload/general settings
- ENV: NORA_RATE_LIMIT_{AUTH|UPLOAD|GENERAL}_{RPS|BURST}
- Rate limit configuration logged at startup
- Functions accept &RateLimitConfig instead of hardcoded values
- Health, metrics, UI, and API docs are now exempt from rate limiting
- Increased upload rate limits to 200 req/s with burst of 500 for Docker compatibility