Delete the provider-error LLMEvent so streams carry output only and
every provider-reported failure exits through the typed error channel.
Anthropic SSE error events, OpenAI Responses response.failed/error
events, and Bedrock exception frames now fail the stream with an
LLMError from the shared classifier (carrying the provider code, e.g.
rate_limit_exceeded -> LLM.RateLimit).
Core follows: the publisher drops its provider-error case, the runner
drops held-back overflow events (overflow recovery keys off a thrown
LLM.ContextOverflow), compaction and title stop scanning events for
failures, and isContextOverflowFailure is deleted with its last
consumer. V1 packages/opencode gets minimal compile fixes only (dead
switch case, one test stream).