Errors and status codes

Handle Foxora API failures by HTTP status, structured error code, and x-request-id, while keeping credentials and prompt content out of logs.

Status	Meaning	Client action
`400`	Invalid request	Fix the payload; do not retry unchanged.
`401`	Authentication failed	Refresh or replace the account token.
`403`	Feature or plan denied	Verify entitlement and requested model.
`404`	Route or resource missing	Check the `/v1` path and identifier.
`429`	Request ceiling reached	Wait for reset guidance and reduce concurrency.
`5xx`	Service failure	Retry safe work with bounded backoff and jitter.

Unknown routes return NOT_FOUND; validation failures return VALIDATION_ERROR; unexpected failures return INTERNAL_ERROR. Upstream-specific messages may vary, so do not build control flow from prose.

Expected result: the client either corrects a permanent request error or performs a bounded retry while retaining the request identifier for support.