api-error-taxonomy

# API Error Taxonomy ## Purpose Define consistent API error codes and responses. ## Inputs to request - Current error responses and status usage. - Client expectations for retries and messaging. - Logging and observability requirements. ## Workflow 1. List common error categories and HTTP mappings. 2. Define error payload shape and fields. 3. Set guidelines for logging and client messaging. ## Output - Error taxonomy table and examples. ## Quality bar - Ensure errors are machine-parseable. - Align retryable vs non-retryable semantics.