- Request translation: add codeWhispererToMessages() to convert CodeWhisperer conversationState to OpenAI messages array
- Response format: replace pipeSSE() with pipeOpenAIasEventStream() to return AWS EventStream binary frames instead of SSE text
- Protocol headers: add required Smithy system headers (:message-type, :event-type, :content-type) to every EventStream frame
- Tool support: add extractTools() to convert CodeWhisperer toolSpecification to OpenAI tool format
- Tool arguments: add safeArgsString() to prevent '[object Object]' corruption during SSE accumulation
- Multi-turn context: add convertAssistantResponseMessage() and convertUserInputMessage() to preserve toolUses and toolResults in history
- Tool dispatch: send toolUseEvent.input as raw JSON string instead of parsed object to match Kiro's internal JSON.parse() expectation
