curl -X POST https://api.llmgenerator.com/api/v1/api-keys/llm_1706123456_abc123def456/regenerate \
  -H "Authorization: Bearer YOUR_API_KEY"

{
  "success": true,
  "message": "API key regenerated successfully",
  "apiKey": {
    "id": "llm_1706123456_abc123def456",
    "name": "Production Key",
    "key": "llm_1706456789_newvalue567xyz",
    "regeneratedAt": "2026-01-27T10:00:00.000Z"
  },
  "warning": "This is the only time the new API key will be shown. Please save it securely. The old key is now invalid."
}