Retrieve YouTube playlist metadata
| Status | Code | Description |
|---|---|---|
| 400 | INVALID_INPUT | Invalid playlist ID format |
| 401 | INVALID_API_KEY | API key is missing or invalid |
| 404 | NOT_FOUND | Playlist not found or private |
| 429 | QUOTA_EXCEEDED | Monthly quota exhausted |
| 429 | RATE_LIMIT_EXCEEDED | Too many requests |