Function isRetryableError

Adapters exports - Model adapters (Claude, OpenAI, Gemini, Ollama) Split from index.ts for file size compliance (Issue #285)

isRetryableError(error: unknown): boolean
Determines if an error is retryable based on its type, status code, or message.

Retryable errors include:
- HTTP 429 (Too Many Requests)
- HTTP 5xx (Server Errors)
- HTTP 408 (Request Timeout)
- Network errors (connection reset, timeout, etc.)
- NexusError with rate limit or timeout codes
Non-retryable errors include:
- HTTP 400, 401, 403, 404 (Client Errors)
- Validation errors
- Authentication errors
Parameters
- error: unknown
  The error to check
Returns boolean
True if the error is retryable
- Defined in packages/nexus-agents/src/adapters/retry.ts:229