* fix: surface real exception class+message in SSE error events
* fix: tighten SSE error patch scope and key redaction
* fix: redact base64-style secret suffixes fully
* style: remove notes/ reference from the dosctring
* fix: rebuild env cache on each error call
* fix: route BaseException through serde.default on SSE/webhook paths
* fix: distinguish routed providers by request URL host
* feat: normalize provider-SDK exceptions via ErrorNormalizationMiddleware
* refactor: drop json_dumpb dataclass-bypass wrappers, superseded by middleware
* fix: guard _extract_host against SDK properties that raise
* refactor: derive provider tag from ModelRequest.model, not the exception
* refactor: drop serde.default patch and exception-based inference; ProviderStreamError.model_dump handles the emit
* refactor: move envelope helpers from patches.py to errors.py
* feat: extend ErrorNormalizationMiddleware coverage to every model-call path
* chore: clean up review findings from middleware pivot
* fix: pass through all langgraph.errors
* fix: move langgraph.errors pass-through into _normalize
* fix: pass through ContextOverflowError in _normalize
jfilipiuk