코워크와 코드 최종 응답 라이브 타이핑 프리뷰 적용

- Cowork/Code 에이전트 루프 완료 후 최종 답변이 한 번에 붙지 않도록 라이브 타이핑 프리뷰를 추가함\n- 처리 중에는 기존 진행 로그를 유지하고, 최종 응답 구간만 스트리밍 컨테이너를 거쳐 자연스럽게 이어지도록 정리함\n- README와 DEVELOPMENT 문서에 2026-04-07 02:31 (KST) 기준 변경 이력 반영\n- 검증: dotnet build src/AxCopilot/AxCopilot.csproj -c Release -v minimal -p:OutputPath=bin\\verify\\ -p:IntermediateOutputPath=obj\\verify\\ (경고 0 / 오류 0)

docs/DEVELOPMENT.md

@@ -5286,3 +5286,4 @@ ow + toggle ?쒓컖 ?몄뼱濡??ㅼ떆 ?뺣젹?덈떎.
 
 - Document update: 2026-04-07 02:23 (KST) - Reconnected the AX Agent direct-chat execution path to the existing SSE/streaming transport in `LlmService`. Chat replies no longer wait for the final full string before rendering; when streaming is enabled they now advance through the existing streaming container and typing-timer path.
 - Document update: 2026-04-07 02:23 (KST) - Updated `AxAgentExecutionEngine.ResolveExecutionMode()` so non-agent chat can opt into streaming transport, and wired `ChatWindow.ExecutePreparedTurnAsync()` to consume `LlmService.StreamAsync(...)` for direct conversations while keeping Cowork/Code on the agent-loop progress-feed path.
+- Document update: 2026-04-07 02:31 (KST) - Added a typed final-response preview for Cowork/Code agent-loop completions. Those tabs still use progress-feed execution during the loop, but once a final assistant answer is available it now passes through the same streaming container/typing presentation before the final transcript message is committed.